Luminal leptin inhibits L-glutamine transport in rat small intestine: involvement of ASCT2 and B0AT1.

L-glutamine is the primary metabolic fuel for enterocytes. Glutamine from the diet is transported into the absorptive cells by two sodium-dependent neutral amino acid transporters present at the apical membrane: ASCT2/SLC1A5 and B(0)AT1/SLC6A19. We have demonstrated that leptin is secreted into the stomach lumen after a meal and modulates the transport of sugars after binding to its receptors located at the brush border of the enterocytes. The present study was designed to address the effect of luminal leptin on Na(+)-dependent glutamine (Gln) transport in rat intestine and identify the transporters involved. We found that 0.2 nM leptin inhibited uptake of Gln and phenylalanine (Phe) (substrate of B(0)AT1) using everted intestinal rings. In Ussing chambers, 10 mM Gln absorption followed as Na(+)-induced short-circuit current was inhibited by leptin in a dose-dependent manner (maximum inhibition at 10 nM; I(C50) = approximately 0.1 nM). Phe absorption was also decreased by leptin. Western blot analysis after 3-min incubation of the intestinal loops with 10 mM Gln, showed marked increase of ASCT2 and B(0)AT1 protein in the brush-border membrane that was reduced by rapid preincubation of the intestinal lumen with 1 nM leptin. Similarly, the increase in ASCT2 and B(0)AT1 gene expression induced by 60-min incubation of the intestine with 10 mM Gln was strongly reduced after a short preincubation period with leptin. Altogether these data demonstrate that, in rat, leptin controls the active Gln entry through reduction of both B(0)AT1 and ASCT2 proteins traffic to the apical plasma membrane and modulation of their gene expression

Análisis del Volumen de Ablación en Diagnóstico Médico mediante Espectroscopía de Plasma Inducido

El análisis de la generación de plasma inducido electromagnéticamente y el procesamiento de inteligencia artificial constituyen una aproximación de interés en el diagnóstico médico. De acuerdo con su alta sensibilidad y capacidad de análisis espectral, la espectroscopia de emisión atómica por plasma surge como respuesta de interés diagnóstico sobre tejidos biológicos. En particular, la espectroscopia de ruptura inducida por láser (LIBS) constituye una herramienta empleada en la caracterización de tejidos biológicos. Esta técnica presenta como efecto la ablación de una parte del tejido bajo análisis, lo que en ocasiones podría generar efectos colaterales no deseados in vivo. En este trabajo se analiza el volumen de ablación inducido electromagnéticamente mediante un modelo computacional basado en el método de Monte Carlo (MC) para estudiar la propagación de la radiación en materiales biológicos. Con esta información es posible estudiar las interacciones radiación-tejido en la ingeniería biomédica. En particular, se utiliza una implementación de un algoritmo de Monte Carlo basado en mallas (MMC) como método para mejorar la precisión en el modelado de tejidos no homogéneos. Se cuantifica el volumen y extensión del tejido ablacionado bajo diferentes parámetros del sistema empleado, fundamentalmente la energía, tiempo de pulso y tiempo de exposición. Los resultados pueden contribuir a la limitación de efectos no deseados en la planificación diagnóstica.Este Trabajo ha sido parcialmente financiado por el proyecto del Plan Nacional de I+D+i “Cribado diagnóstico de microorganismos mediante microscopia avanzada e inteligencia artificial en patologías humana” (PID2021- 127691OB-I00), del Ministerio de Ciencia e Innovación, cofinanciado con fondos FEDER, y por la Fundación Carolina a través de la beca concedida a R. Sosa-Santos

The weighted independent domination problem: ILP model and algorithmic approaches

This work deals with the so-called weighted independent domination problem, which is an N P -hard combinatorial optimization problem in graphs. In contrast to previous theoretical work from the liter- ature, this paper considers the problem from an algorithmic perspective. The first contribution consists in the development of an integer linear programming model and a heuristic that makes use of this model. Sec- ond, two greedy heuristics are proposed. Finally, the last contribution is a population-based iterated greedy algorithm that takes profit from the better one of the two developed greedy heuristics. The results of the compared algorithmic approaches show that small problem instances based on random graphs are best solved by an efficient integer linear programming solver such as CPLEX. Larger problem instances are best tackled by the population-based iterated greedy algorithm. The experimental evaluation considers random graphs of different sizes, densities, and ways of generating the node and edge weights

The Weighted Independent Domination Problem: ILP Model and Algorithmic Approaches

This work deals with the so-called weighted independent domination problem, which is an $NP$-hard combinatorial optimization problem in graphs. In contrast to previous work, this paper considers the problem from a non-theoretical perspective. The first contribution consists in the development of three integer linear programming models. Second, two greedy heuristics are proposed. Finally, the last contribution is a population-based iterated greedy metaheuristic which is applied in two different ways: (1) the metaheuristic is applied directly to each problem instance, and (2) the metaheuristic is applied at each iteration of a higher-level framework---known as construct, merge, solve \& adapt---to sub-instances of the tackled problem instances. The results of the considered algorithmic approaches show that integer linear programming approaches can only compete with the developed metaheuristics in the context of graphs with up to 100 nodes. When larger graphs are concerned, the application of the populated-based iterated greedy algorithm within the higher-level framework works generally best. The experimental evaluation considers graphs of different types, sizes, densities, and ways of generating the node and edge weights

Leptin regulates sugar and amino acids transport in the human intestinal cell line Caco-2

Aim: Studies in rodents have shown that leptin controls sugars and glutamine entry in the enterocytes by regulating membrane transporters. Here, we have examined the effect of leptin on sugar and amino acids absorption in the human model of intestinal cells Caco-2 and investigated the transporters involved. Methods: Substrate uptake experiments were performed in Caco-2 cells, grown on plates, in the presence and the absence of leptin and the expression of the different transporters in brush border membrane vesicles was analysed by Western blot. Results: Leptin inhibited 0.1 mM α-methyl-D-glucoside uptake after 5 or 30 min treatment, and decreased SGLT1 protein abundance in the apical membrane. Uptake of 20 µM glutamine and 0.1 mM phenylalanine was also inhibited by leptin, indicating sensitivity to the hormone of the Na+-dependent neutral amino acid transporters ASCT2 and B0AT1. This inhibition was accompanied by a reduction of the transporters expression at the brush-border membrane. Leptin also inhibited 1 mM proline and β-alanine uptake in Na+ medium at pH 6, conditions for optimal activity of the H+-dependent neutral amino acid transporter PAT1. In this case, abundance of PAT1 in the brush-border membrane after leptin treatment was not modified. Interestingly, leptin inhibitory effect on β-alanine uptake was reversed by the PKA inhibitor H-89 suggesting involvement of PKA pathway in leptin´s regulation of PAT1 activity. Conclusion: These data show in human intestinal cells that leptin can rapidly control the activity of physiologically relevant transporters for rich-energy molecules, i.e D-glucose (SGLT1) and amino acids (ASCT2, B0AT1 and PAT1)

Insulin but not phorbol ester treatment increases phosphorylation of vinculin by protein kinase C in BC3H-1 myocytes

AbstractInsulin was found to increase protein kinase C activity in BC3H-1 myocytes as determined by in vitro phosphorylation of both a lysine-rich histone fraction (histone III-S) and vinculin. TPA treatment for 20 min or 18 h provoked an apparent loss of histone-directed but not vinculin-directed phosphorylation by cytosolic C-kinase. Thus, chronic TPA-induced ‘desensitization’ or ‘depletion’ of cellular protein kinase C is more apparent than real, and is not a valid means for evaluating the role of C-kinase in hormone action

The response of the tandem pore potassium channel TASK-3 (K2P9.1) to voltage : gating at the cytoplasmic mouth

Although the tandem pore potassium channel TASK-3 is thought to open and shut at its selectivity filter in response to changes of extracellular pH, it is currently unknown whether the channel also shows gating at its inner, cytoplasmic mouth through movements of membrane helices M2 and M4.We used two electrode voltage clamp and single channel recording to show that TASK-3 responds to voltage in a way that reveals such gating. In wild-type channels, Popen was very low at negative voltages, but increased with depolarisation. The effect of voltage was relatively weak and the gating charge small, ∼0.17.Mutants A237T (in M4) and N133A (in M2) increased Popen at a given voltage, increasing mean open time and the number of openings per burst. In addition, the relationship between Popen andvoltagewas shifted to lesspositive voltages. Mutation of putative hinge glycines (G117A, G231A), residues that are conserved throughout the tandem pore channel family, reduced Popen at a given voltage, shifting the relationship with voltage to a more positive potential range. None of these mutants substantially affected the response of the channel to extracellular acidification. We have used the results from single channel recording to develop a simple kinetic model to show how gating occurs through two classes of conformation change, with two routes out of the open state, as expected if gating occurs both at the selectivity filter and at its cytoplasmic mouth

Asymmetric Organocatalysis in Deep Eutectic Solvents

The recent advances in asymmetric organocatalysis using eutectic mixtures as a reaction medium are revised in this mini‐review. In addition, the first enantioselective transformations using chiral eutectic solvents, which play the role of a green medium and organocatalyst, are described. In this mini‐review we intend to deepen not only in the synthetic aspects of asymmetric organocatalysis in eutectic mixtures, but also in the fundamental issues that seem to be essential for a successful development of this promising, and at the same time challenging, methodology.This work was supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN, PGC2018-096616-B-I00), the University of Alicante (VIGROB-173 and VIGROB-316FI), and the University of Pisa (PRA_2018_36)