Dinâmica Físico-Química de Águas Superficiais em Região de Intensa Criação de Suínos: Exemplo da Bacia Hidrográfica do Rio Coruja-Bonito, Município de Braço do Norte, SC.

A dinâmica físico-química das águas superficiais da bacia hidrográfica do rio CorujaBonito, em Braço do Norte, SC é relacionada com o impacto ambiental dos dejetos gerados pelo modelo de suinocultura intensiva ali adotado. As análises da temperatura, pH, OD, coliformes, DQO, DBO, turbidez, sólidos totais, amônia, nitratos, nitritos, fósforo total, sulfatos, sulfetos, ABS e vazão mostram que os principais parâmetros, e em especial o oxigênio dissolvido (OD), dependem da liberação direta ou indireta dos dejetos na água. A análise do perfil longitudinal do rio é de fundamental importância para compreender o comportamento físico-químico dos poluentes

Evolução do uso do solo e agronegócio na região oeste do Estado da Bahia.

Este artigo apresenta uma análise da evolução do uso do solo na região de Barreiras. Utilizou-se imagens de satélite Landsat-5 (1984 e 2008) e imagens SRTM, processadas no programa Spring. Foram considerados a implantação do agronegócio na região e aspectos do meio físico. A declividade predominante é inferior a 5%, exceto nas bordas dos planaltos; a altitude está em torno de 500-700 metros. A introdução do agronegócio trouxe mudanças espaciais na área, com crescimento da área urbana e alterações na distribuição da vegetação, com importante da área agrícola e redução da vegetação de cerrado

Ophthalmic magnetic resonance imaging at 7.0 T using a 6-channel transceiver radiofrequency coil array in healthy subjects and patients with intraocular masses

OBJECTIVES: This study was designed to examine the feasibility of ophthalmic magnetic resonance imaging (MRI) at 7.0 T using a local 6-channel transmit/receive radiofrequency (RF) coil array in healthy volunteers and patients with intraocular masses. MATERIALS AND METHODS: A novel 6-element transceiver RF coil array that makes uses of loop elements and that is customized for eye imaging at 7.0 T is proposed. Considerations influencing the RF coil design and the characteristics of the proposed RF coil array are presented. Numerical electromagnetic field simulations were conducted to enhance the RF coil characteristics. Specific absorption rate simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Phantom experiments were carried out to validate the electromagnetic field simulations and to assess the real performance of the proposed transceiver array. Certified approval for clinical studies was provided by a local notified body before the in vivo studies. The suitability of the RF coil to image the human eye, optical nerve, and orbit was examined in an in vivo feasibility study including (a) 3-dimensional (3D) gradient echo (GRE) imaging, (b) inversion recovery 3D GRE imaging, and (c) 2D T2-weighted fast spin-echo imaging. For this purpose, healthy adult volunteers (n = 17; mean age, 34 +- 11 years) and patients with intraocular masses (uveal melanoma, n = 5; mean age, 57 +- 6 years) were investigated. RESULTS: All subjects tolerated all examinations well with no relevant adverse events. The 6-channel coil array supports high-resolution 3D GRE imaging with a spatial resolution as good as 0.2 × 0.2 × 1.0 mm, which facilitates the depiction of anatomical details of the eye. Rather, uniform signal intensity across the eye was found. A mean signal-to-noise ratio of approximately 35 was found for the lens, whereas the vitreous humor showed a signal-to-noise ratio of approximately 30. The lens-vitreous humor contrast-to-noise ratio was 8, which allows good differentiation between the lens and the vitreous compartment. Inversion recovery prepared 3D GRE imaging using a spatial resolution of 0.4 × 0.4 × 1.0 mm was found to be feasible. T2-weighted 2D fast spin-echo imaging with the proposed RF coil afforded a spatial resolution of 0.25 × 0.25 × 0.7 mm. CONCLUSIONS: This work provides valuable information on the feasibility of ophthalmic MRI at 7.0 T using a dedicated 6-channel transceiver coil array that supports the acquisition of high-contrast, high-spatial resolution images in healthy volunteers and patients with intraocular masses. The results underscore the challenges of ocular imaging at 7.0 T and demonstrate that these issues can be offset by using tailored RF coil hardware. The benefits of such improvements would be in positive alignment with explorations that are designed to examine the potential of MRI for the assessment of spatial arrangements of the eye segments and their masses with the ultimate goal to provide imaging means for guiding treatment decisions in ophthalmological diseases

Evaluation of rate law approximations in bottom-up kinetic models of metabolism.

BackgroundThe mechanistic description of enzyme kinetics in a dynamic model of metabolism requires specifying the numerical values of a large number of kinetic parameters. The parameterization challenge is often addressed through the use of simplifying approximations to form reaction rate laws with reduced numbers of parameters. Whether such simplified models can reproduce dynamic characteristics of the full system is an important question.ResultsIn this work, we compared the local transient response properties of dynamic models constructed using rate laws with varying levels of approximation. These approximate rate laws were: 1) a Michaelis-Menten rate law with measured enzyme parameters, 2) a Michaelis-Menten rate law with approximated parameters, using the convenience kinetics convention, 3) a thermodynamic rate law resulting from a metabolite saturation assumption, and 4) a pure chemical reaction mass action rate law that removes the role of the enzyme from the reaction kinetics. We utilized in vivo data for the human red blood cell to compare the effect of rate law choices against the backdrop of physiological flux and concentration differences. We found that the Michaelis-Menten rate law with measured enzyme parameters yields an excellent approximation of the full system dynamics, while other assumptions cause greater discrepancies in system dynamic behavior. However, iteratively replacing mechanistic rate laws with approximations resulted in a model that retains a high correlation with the true model behavior. Investigating this consistency, we determined that the order of magnitude differences among fluxes and concentrations in the network were greatly influential on the network dynamics. We further identified reaction features such as thermodynamic reversibility, high substrate concentration, and lack of allosteric regulation, which make certain reactions more suitable for rate law approximations.ConclusionsOverall, our work generally supports the use of approximate rate laws when building large scale kinetic models, due to the key role that physiologically meaningful flux and concentration ranges play in determining network dynamics. However, we also showed that detailed mechanistic models show a clear benefit in prediction accuracy when data is available. The work here should help to provide guidance to future kinetic modeling efforts on the choice of rate law and parameterization approaches

Metabolic flux understanding of Pichia pastoris grown on heterogenous culture media

[EN] Within the emergent field of Systems Biology, mathematical models obtained from physical chemical laws (the so-called first principles-based models) of microbial systems are employed to discern the principles that govern cellular behaviour and achieve a predictive understanding of cellular functions. The reliance on this biochemical knowledge has the drawback that some of the assumptions (specific kinetics of the reaction system, unknown dynamics and values of the model parameters) may not be valid for all the metabolic possible states of the network. In this uncertainty context, the combined use of fundamental knowledge and data measured in the fermentation that describe the behaviour of the microorganism in the manufacturing process is paramount to overcome this problem. In this paper, a grey modelling approach is presented combining data-driven and first principles information at different scales, developed for Pichia pastoris cultures grown on different carbon sources. This approach will allow us to relate patterns of recombinant protein production to intracellular metabolic states and correlate intra and extracellular reactions in order to understand how the internal state of the cells determines the observed behaviour in P. pastoris cultivations.Research in this study was partially supported by the Spanish Ministry of Science and Innovation and FEDER funds from the European Union through grants DPI2011-28112-C04-01 and DPI2011-28112-C04-02. The authors are also grateful to Biopolis SL for supporting this research. We also gratefully acknowledge Associate Professor Jose Camacho for providing the Exploratory Data Analysis Toolbox.González Martínez, JM.; Folch-Fortuny, A.; Llaneras Estrada, F.; Tortajada Serra, M.; Picó Marco, JA.; Ferrer, A. (2014). Metabolic flux understanding of Pichia pastoris grown on heterogenous culture media. Chemometrics and Intelligent Laboratory Systems. 134:89-99. https://doi.org/10.1016/j.chemolab.2014.02.003S899913

MCR-ALS on metabolic networks: Obtaining more meaningful pathways

[EN] With the aim of understanding the flux distributions across a metabolic network, i.e. within living cells, Principal Component Analysis (PCA) has been proposed to obtain a set of orthogonal components (pathways) capturing most of the variance in the flux data. The problems with this method are (i) that no additional information can be included in the model, and (ii) that orthogonality imposes a hard constraint, not always reasonably. To overcome these drawbacks, here we propose to use a more flexible approach such as Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) to obtain this set of biological pathways through the network. By using this method, different constraints can be included in the model, and the same source of variability can be present in different pathways, which is reasonable from a biological standpoint. This work follows a methodology developed for Pichia pastoris cultures grown on different carbon sources, lately presented in González-Martínez et al. (2014). In this paper a different grey modelling approach, which aims to incorporate a priori knowledge through constraints on the modelling algorithms, is applied to the same case of study. The results of both models are compared to show their strengths and weaknesses.Research in this study was partially supported by the Spanish Ministry of Science and Innovation and FEDER funds from the European Union through grants DPI2011-28112-C04-01 and DPI2011-28112-C04-02. The authors are also grateful to Biopolis SL for supporting this research.Folch-Fortuny, A.; Tortajada Serra, M.; Prats-Montalbán, JM.; Llaneras Estrada, F.; Picó Marco, JA.; Ferrer Riquelme, AJ. (2015). MCR-ALS on metabolic networks: Obtaining more meaningful pathways. Chemometrics and Intelligent Laboratory Systems. 142:293-303. https://doi.org/10.1016/j.chemolab.2014.10.004S29330314

In vivo imaging of pancreatic tumours and liver metastases using 7 Tesla MRI in a murine orthotopic pancreatic cancer model and a liver metastases model

<p>Abstract</p> <p>Background</p> <p>Pancreatic cancer is the fourth leading cause of tumour death in the western world. However, appropriate tumour models are scarce. Here we present a syngeneic murine pancreatic cancer model using 7 Tesla MRI and evaluate its clinical relevance and applicability.</p> <p>Methods</p> <p>6606PDA murine pancreatic cancer cells were orthotopically injected into the pancreatic head. Liver metastases were induced through splenic injection. Animals were analyzed by MRI three and five weeks following injection. Tumours were detected using T2-weighted high resolution sequences. Tumour volumes were determined by callipers and MRI. Liver metastases were analyzed using gadolinium-EOB-DTPA and T1-weighted 3D-Flash sequences. Tumour blood flow was measured using low molecular gadobutrol and high molecular gadolinium-DTPA.</p> <p>Results</p> <p>MRI handling and applicability was similar to human systems, resolution as low as 0.1 mm. After 5 weeks tumour volumes differed significantly (p < 0.01) when comparing calliper measurments (n = 5, mean 1065 mm³+/-243 mm³) with MRI (mean 918 mm³+/-193 mm³) with MRI being more precise. Histology (n = 5) confirmed MRI tumour measurements (mean size MRI 38.5 mm²+/-22.8 mm²versus 32.6 mm²+/-22.6 mm²(histology), p < 0,0004) with differences due to fixation and processing of specimens. After splenic injection all mice developed liver metastases with a mean of 8 metastases and a mean volume of 173.8 mm³+/-56.7 mm³after 5 weeks. Lymphnodes were also easily identified. Tumour accumulation of gadobutrol was significantly (p < 0.05) higher than gadolinium-DTPA. All imaging experiments could be done repeatedly to comply with the 3R-principle thus reducing the number of experimental animals.</p> <p>Conclusions</p> <p>This model permits monitoring of tumour growth and metastasis formation in longitudinal non-invasive high-resolution MR studies including using contrast agents comparable to human pancreatic cancer. This multidisciplinary environment enables radiologists, surgeons and physicians to further improve translational research and therapies of pancreatic cancer.</p