Effect of thapsigargin on calcium homeostasis in Trypanosoma cruzi trypomastigotes and epimastigotes

By using the fluorescent calcium indicator fura-2, it was found that the concentration of free Ca2+ in the cytoplasm of Trypanosoma cruzi trypomastigotes incubated in the presence or absence of external calcium was maintained at very low levels (10-20 nM). When trypomastigotes were incubated in the presence of succinate and ATP and permeabilized with digitonin, they lowered the medium calcium concentration to a submicromolar level. In the presence of 1 microM FCCP the initial rate of Ca2+ sequestration by these permeabilized cells was very slow. When succinate alone was present, the initial rate of Ca2+ accumulation was slower than with ATP plus succinate, and the calcium set point was about 0.6 microM. The succinate dependence and FCCP sensitivity of the later Ca2+ uptake indicate that it may be exerted by the mitochondria. High concentrations of the tumor promoter thapsigargin slightly increased cytosolic Ca2+ in the presence of extracellular Ca2+ but had no effect on the FCCP- and oligomycin/antimycin A-insensitive Ca2+ pool. In addition, when used at those concentrations (4-20 microM), thapsigargin was shown to release Ca2+ from the mitochondria and to decrease the inner mitochondrial membrane potential of trypomastigotes and epimastigotes as measured using safranine O. Despite the presence of inositol phosphates as determined by [3H]inositol incorporation, no IP3-sensitive Ca2+ release could be detected in trypomastigotes.     

Effect of the impact angle on the breakage of agglomerates: a numerical study using DEM

The study of agglomerate strength is of vital importance in several industrial applications such as pharmaceutical, detergent and food manufacturing. Agglomerates could experience a size reduction during the production and handling processes due to collisions with other agglomerates or with the moving components and walls as well as during bulk flow due to shear deformation. In this analysis, we focus on the agglomerate damage due to oblique impact on walls, as this is a common damage process during, for example, pneumatic conveying and size reduction in pin mills.

Computer simulations have been carried out using Distinct Element Analysis, where the breakage characteristics of oblique impacts and the effect of the interparticle bond strength have been analysed. The procedure adopted here provides an isotropic and spherical agglomerate (uniform mass distribution and coordination number within radial segments of the agglomerate). The results indicate that the damage ratio (i.e. the number fraction of the broken bonds) depends on the normal component of the impact velocity only, i.e. the tangential component has little effect. However, the position of the clusters produced on impact does depend on the impact angle, which influences the pattern of breakage and in turn the size distribution of the large clusters.     

Antiproteinuric effect of angiotensin-converting enzyme inhibition and C5b-9 urinary excretion in membranous glomerulonephritis

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors have an antiproteinuric effect in membranous glomerulonephritis (MGN). However, no studies have investigated whether this antiproteinuric effect is influenced by urinary C5b-9 excretion, a marker of immunological activity in this disease. METHODS: Eleven patients with biopsy-proven MGN were treated with captopril for 8 weeks. The evolution of several clinical and biochemical parameters, including 24-h urinary protein excretion was evaluated every 4 weeks. Urinary C5b-9 excretion was measured at the onset and at the end of captopril treatment. RESULTS: Patients with MGN had significantly higher C5b-9 excretions than a group of 14 healthy controls (89 +/- 23 vs 3.7 +/- 1.4 ng/mg UCr; P < 0.001). A significant correlation was found between urinary C5b-9 and the magnitude of proteinuria, both at the onset and at the end of treatment. After 8 weeks of captopril treatment, proteinuria had decreased from 8 +/- 1.8 to 5.2 +/- 1.3 g/day (P < 0.05). Four weeks after captopril discontinuation, proteinuria rose to 7.3 +/- 1.7 g/day (P < 0.05). A marked variability in the antiproteinuric response was observed, ranging from 0 to 85% with respect to baseline values. No correlation between decrease in proteinuria and baseline urinary C5b-9 levels was observed. Several patients with elevated urinary C5b-9 levels had captopril-induced decrease in proteinuria. CONCLUSIONS: ACE inhibition induces an antiproteinuric effect in patients with MGN. The urinary C5b-9 excretion does not predict the magnitude of this response.     

Response time variability

Response time variability is a new optimization problem with a broad range of applications and a distinctive number of theoretic flavour. The problem occurs whenever events, jobs, clients or products need to be sequenced so as to minimize the variability of time for which they wait for the next turn in obtaining the resources necessary for their advance. The problem has numerous real-life applications. We study its computational complexity, present efficiency, polynomial time algorithms for some cases, and the NP-hardness proof for a general problem. We propose a position exchange heuristic and apply it to improve the total response time variability of an initial sequence. The latter is the optimum bottleneck sequence, Webster or Jefferson sequence of the apportionment, or a random sequence. We report on computational experiments with the heuristic.     

Identification of naturally isolated Southern Louisiana's algal strains and the effect of higher CO2 content on fatty acid profiles for biodiesel production

BACKGROUND: Microalgae, with both high biomass productivity and oil content, are regarded as attractive candidates for the production of alternative biodiesel as well as for CO₂ biofixation. In the present study, four microalgal strains native to southeastern Louisiana's waters were isolated and identified to evaluate their potential for the production of biodiesel. Selected strains were identified through genomic DNA in sequencing of either 16S rRNA or 18S rRNA genes followed by lipid and fatty acid content characterization and quantification. RESULTS: High correlation was found with known nucleotide sequence identities at 98% with Sellaphora pupula, and 99% with Synechococcus sp., Chlorella sorokiniana, Scenedesmus abundans, and Chlorella vulgaris (control). The fatty acid profiles of these organisms changed when using 5% CO₂ aeration. Total fatty acids (TFA) decreased from 20.63 to 17.62, 54.83 to 24.4, and 29.82 to 23.99 g kg^?1 in Synechococcus sp., Sellaphora pupula and Chlorella sorokiniana, respectively. TFA increased from 14.14 to 31.49 and 15.14 to 47.52 g kg^?1 dry biomass in Scenedesmus abundans and Chlorella vulgaris (control), respectively. CONCLUSION: Chlorella sorokiniana, with a lower C18:3 and the highest biomass yield at 5% CO₂ aeration, was found to be the best candidate for biodiesel production. © 2012 Society of Chemical Industry     

Assessment of the final metrological characteristics of a MOEMS-based NDIR spectrometer through system modeling and data processing

A model of a miniaturized non-dispersive infrared (NDIR) gas analysis system, aiming to predict the final system specifications, is presented. It comprises the different elements of the NDIR detector, including a surface micromachined Fabry-Perot tunable filter. These models have been used to estimate the response of the NDIR system to different gas mixtures. Multivariate regression methods like partial least squares allow recovering the true sample composition from the IR absorption spectra measured with the NDIR system, despite the limited selectivity of the filter. Combining model and data processing permits to predict the effect on the final system specification of design parameters. Here, we compare the effect of the technology used for the filter on the system errors.     

The role of Smart Grids to foster energy efficiency

The traditional electricity grid has remained the same for most of last century, without major architectural improvements. However, its requirements, guidelines and goals do have changed, especially during the last few years, driven by the sustainability in energy generation and energy efficiency principles. Thus, taking greenhouse gases emissions and CO₂ footprint reduction as key objectives and information and communications technologies as key enabler technologies, a novel and revolutionary electric grid paradigm, the so-called Smart Grid, is emerging, in which energy efficiency and renewable generation play a central role. This paper presents an overview on the main requirements and features of Smart Grids to integrate energy efficiency, on the work done and to be done, on the enabler technologies, as well as on the expected impacts and the main benefits Smart Grids will bring.