The Barcelona Predictive Model of Clinically Significant Prostate Cancer.

A new and externally validated MRI-PM for csPCa was developed in the metropolitan area of Barcelona, and a web-RC designed with the new option of selecting the csPCa probability threshold. The development cohort comprised 1486 men scheduled to undergo a 3-tesla multiparametric MRI (mpMRI) and guided and/or systematic biopsies in one academic institution of Barcelona. The external validation cohort comprised 946 men in whom the same diagnostic approach was carried out as in the development cohort, in two other academic institutions of the same metropolitan area. CsPCa was detected in 36.9% of men in the development cohort and 40.8% in the external validation cohort (p = 0.054). The area under the curve of mpMRI increased from 0.842 to 0.897 in the developed MRI-PM (p < 0.001), and from 0.743 to 0.858 in the external validation cohort (p < 0.001). A selected 15% threshold avoided 40.1% of prostate biopsies and missed 5.4% of the 36.9% csPCa detected in the development cohort. In men with PI-RADS <3, 4.3% would be biopsied and 32.3% of all existing 4.2% of csPCa would be detected. In men with PI-RADS 3, 62% of prostate biopsies would be avoided and 28% of all existing 12.4% of csPCa would be undetected. In men with PI-RADS 4, 4% of prostate biopsies would be avoided and 0.6% of all existing 43.1% of csPCa would be undetected. In men with PI-RADS 5, 0.6% of prostate biopsies would be avoided and none of the existing 42.0% of csPCa would be undetected. The Barcelona MRI-PM presented good performance on the overall population; however, its clinical usefulness varied regarding the PI-RADS category. The selection of csPCa probability thresholds in the designed RC may facilitate external validation and outperformance of MRI-PMs in specific PI-RADS categories.

Metabolic flux balance analysis during lactate and glucose concomitant consumption in HEK293 cell cultures.

At early stages of the exponential growth phase in HEK293 cell cultures, the tricarboxylic acid cycle is unable to process all the amount of NADH generated in the glycolysis pathway, being lactate the main by-product. However, HEK293 cells are also able to metabolize lactate depending on the environmental conditions. It has been recently observed that one of the most important modes of lactate metabolization is the cometabolism of lactate and glucose, observed even during the exponential growth phase. Extracellular lactate concentration and pH appear to be the key factors triggering the metabolic shift from glucose consumption and lactate production to lactate and glucose concomitant consumption. The hypothesis proposed for triggering this metabolic shift to lactate and glucose concomitant consumption is that HEK293 cells metabolize extracellular lactate as a response to both extracellular protons and lactate accumulation, by means of cotransporting them (extracellular protons and lactate) into the cytosol. At this point, there exists a considerable controversy about how lactate reaches the mitochondrial matrix: the first hypothesis proposes that lactate is converted into pyruvate in the cytosol, and afterward, pyruvate enters into the mitochondria; the second alternative considers that lactate enters first into the mitochondria, and then, is converted into pyruvate. In this study, lactate transport and metabolization into mitochondria is shown to be feasible, as evidenced by means of respirometry tests with isolated active mitochondria, including the depletion of lactate concentration of the respirometry assay. Although the capability of lactate metabolization by isolated mitochondria is demonstrated, the possibility of lactate being converted into pyruvate in the cytosol cannot be excluded from the discussion. For this reason, the calculation of the metabolic fluxes for an HEK293 cell line was performed for the different metabolic phases observed in batch cultures under pH controlled and noncontrolled conditions, considering both hypotheses. The main objective of this study is to evaluate the redistribution of cellular metabolism and compare the differences or similarities between the phases before and after the metabolic shift of HEK293 cells (shift observed when pH is not controlled). That is from a glucose consumption/lactate production phase to a glucose-lactate coconsumption phase. Interestingly, switching to a glucose and lactate cometabolization results in a better-balanced cell metabolism, with decreased glucose and amino acids uptake rates, affecting minimally cell growth. This behavior could be applied to further develop new approaches in terms of cell engineering and to develop improved cell culture strategies in the field of animal cell technology.

Structural changes of Arthrospira sp. after low energy sonication treatment for microalgae harvesting: Elucidating key parameters to detect the rupture of gas vesicles.

The buoyancy suppression by low energy sonication (LES) treatment (0.8W·mL-1, 20kHz, 10s) has recently been proposed as an initial harvesting step for Arthrospira sp. This paper aims to describe the structural changes in Arthrospira sp. after LES treatment and to present how these structural changes affect the results obtained by different analytical techniques. Transmission electron microscopy (TEM) micrographs of trichomes evidenced the gas vesicles rupture but also revealed a rearrangement of thylakoids and more visible phycobilisomes were observed. Differences between treated and untreated samples were detected by confocal microscopy, flow cytometry and optical microscopy but not by electrical impedance spectroscopy (EIS). After LES treatment, 2-fold increase in autofluorescence at 610/660nm was measured (phycocyanin/allophycocyanin emission wavelengths) and a ten-fold decrease in side scatter light intensity (due to a reduction of trichome's inner complexity). This was further confirmed by optical microscopy showing changes on trichomes appearance (from wrinkled to smooth).

Not just like starting over - Leadership and revivification of cooperation in groups.

We conduct a laboratory experiment to study how, after a history of decay, cooperation in a repeated voluntary contribution game can be revived in an enduring way. Simply starting the repeated game over-a simple fresh start-leads to an initial increase of cooperation, but to a subsequent new decay. Motivated by cooperation decay in organizations we study the potential of three interventions of triggering higher and sustained cooperation, which take place at the same time as a restart. Surprisingly, we find that the detailed explanation of the causes of the decay in cooperation of Fischbacher and Gächter (Am Econ Rev 100:541-556, 2010) combined with an advice on how to prevent decay do not have an effect beyond that of just starting over. In contrast, a one-way free form communication message sent by the leader to the followers strongly revives cooperation. We find evidence that repeated free form communication by the leader further strengthens the reviving effect on cooperation. Combining the two previous interventions does not outperform the pure effect of communication. Our content analysis reveals that leader communication is more people oriented than the expert advice.

Optimization of ferric chloride concentration and pH to improve both cell growth and flocculation in Chlorella vulgaris cultures. Application to medium reuse in an integrated continuous culture bioprocess.

Combined effect of ferric chloride and pH on Chlorella vulgaris growth and flocculation were optimized using DoE. Afterwards, an integrated bioprocess for microalgae cultivation and harvesting conceived as a sole step was run in continuous operation mode. Microalgae concentration in a 2L-photobioreactor was about 0.5gL(-1) and the efficiency of flocculation in the coupled sedimentation tank was about 95%. Dewatered microalgae reached a biomass concentrations increase about 50-fold, whereas it was only about 0.02gL(-1) in the clarified medium. Then, the reuse of the clarified medium recovered was further evaluated. The clarified medium was reused without any further nutrient supplementation, whereas a second round of medium reuse was performed after supplementation of main nutrients (phosphate-sulfate-nitrate), micronutrients and ferric chloride. The medium reuse strategy did not affect cell growth and flocculation. Consequently, the reuse of medium reduces the nutrients requirements and the demand for water, and therefore the production costs should be reduced accordingly.

Lactate and glucose concomitant consumption as a self-regulated pH detoxification mechanism in HEK293 cell cultures.

One of the most important limitations of mammalian cell-based processes is the secretion and accumulation of lactate as a by-product of their metabolism. Among the cell lines commonly used in industrial bioprocesses, HEK293 has been gaining importance over the last years. Up recently, HEK293 cells were known to consume lactate in late stages of cell culture usually when glucose and/or glutamine were depleted from media. Remarkably, in both scenarios, no significant cell growth was reported. However, we have observed a different metabolic behavior regarding lactate production and consumption in HEK293 cultures. HEK293 cells were able to co-metabolize glucose and lactate simultaneously, even in exponentially growing cell cultures. Our deep study of the effects of environmental conditions on lactate metabolism revealed that pH was the key to trigger the metabolic shift from lactate production to lactate and glucose concomitant consumption. Remarkably, this shift could be triggered at will when pH was set at 6.8. Even more interesting was the fact that lowering pH to 6.6 and supplementing media with exogenous lactate resulted in co-consumption of glucose and lactate from the beginning of cell culture, without affecting cell growth or protein productivity. On the contrary, cell growth was clearly hampered at this low pH if extracellular lactate was lacking. From our results, we hypothesize that HEK293 cells metabolize extracellular lactate as a strategy for pH detoxification, by means of co-transporting extracellular protons together with lactate into the cytosol. This novel hypothesis for unraveling lactate metabolism in HEK293 cells could open a door to re-direct genetic engineering strategies in order to obtain more efficient cell lines and also to further develop animal cell technology applications.