An almost third order finite difference scheme for singularly perturbed reaction–diffusion systems

AbstractThis paper addresses the numerical approximation of solutions to coupled systems of singularly perturbed reaction–diffusion problems. In particular a hybrid finite difference scheme of HODIE type is constructed on a piecewise uniform Shishkin mesh. It is proved that the numerical scheme satisfies a discrete maximum principle and also that it is third order (except for a logarithmic factor) uniformly convergent, even for the case in which the diffusion parameter associated with each equation of the system has a different order of magnitude. Numerical examples supporting the theory are given

High order schemes for reaction-diffusion singularly perturbed systems

In this paper we are interested in solving e¿ciently a singularly per-turbed linear system of di¿erential equations of reaction-di¿usion type. Firstly, anon–monotone ¿nite di¿erence scheme of HODIE type is constructed on a Shishkinmesh. The previous method is modi¿ed at the transition points such that an inversemonotone scheme is obtained. We prove that if the di¿usion parameters are equal itis a third order uniformly convergent method. If the di¿usion parameters are di¿er-ent some numerical evidence is presented to suggest that an uniformly convergentscheme of order greater than two is obtained. Nevertheless, the uniform errors arebigger and the orders of uniform convergence are less than in the case correspondingto equal di¿usion parameters

Compression of the Left Innominated Vein between the Brachiocephalic Trunk and Left Carotid Artery

AbstractWe present a case of a 25-year-old male who looked for medical attention for symptoms like dysesthesias in his left arm. Physical examination revealed severe dilations of the superficial veins in his left forearm and arm.An ultrasound showed no signs of thrombosis. Dynamic phlebography ruled out the presence of extrinsic compression of the left innominated vein. The angioMRI confirmed that the innominated vein was compressed between the braquiocephalic trunk and left carotid.Therefore, we describe a previously unreported congenital anomaly of the left brachiocephalic vein where the fundamental symptom is the compression of the left innominated trunk

Combined Treatment with Open and Endovascular Surgery of a Mycotic Abdominal Aortic Aneurysm

AbstractWe report the treatment of a 67-year-old male patient with a suprarenal mycotic aortic aneurysm. A 67-year-old male developed renal failure during the treatment of a urine infection and a paracervical abscess. Further investigations revealed a 5.6cm saccular suprarenal abdominal aortic aneurysm. A successful combined treatment was carried out with endovascular techniques and open surgery, realizing a retrograde aorto-superior mesenteric bypass. Postoperative follow up scans showed exclusion and thrombosis of the aneurysm. Treatment of mycotic aneurysms is mainly surgical, but endovascular therapy helps to avoid highly complicated surgery and reduces mortality

Efecto de un inhibidor de la vía paracelular (2, 4, 6 Triaminopirimidina) sobre el movimiento de agua y electrolitos en íleon y colon de conejo “in vitro” e “in vivo”

Se estudia la influencia de un inhibidor de la vía paracelular 2, 4, 6 Triaminopirimidina (T AP) sobre el movimiento de agua y electrolitos en ileon distal y colon proximal de conejo "in vitro" e "in vivo". "In vitro" el TAP disminuye marcadamente la absorción de sodio, cloruro y aumenta la secreción de potasio, inviertiendo la transferencia de bicarbonato hacia la secreción. "In vivo" el T AP a nivel ileal tiene un efecto similar al indicado "in vitro", si bien las diferencias son menos importantes, mientras que a nivel de colon ocurre todo lo contrario, aunque estos cambios no son importantes.The influence of an inhibitor of the paracellular pathways (2, 4, 6 Triaminopirimidine, T AP) on the movemente of water and electrolytes, in distal ileum and proximal colon of rabbit "in vitro" and "in vivo", have been studied. "In vitro" the TAP significantly decreased the absorption of sodium, chloride and raised the secretion of potassium, reversing the transference of bicarbonate to the secretion, both in ileum and colon. "In vivo" the T AP at ileal level had a similar effect than "in vitro", al though the differences were less important. In the colon the changes were just the opposite, but they were no significative differences

Efecto de un inhibidor de la vía paracelular (2, 4, 6 Triaminopirimidina) sobre el movimiento de agua y electrolitos en íleon y colon de conejo “in vitro” e “in vivo”

The influence of an inhibitor of the paracellular pathways (2, 4, 6 Triaminopirimidine, T AP) on the movemente of water and electrolytes, in distal ileum and proximal colon of rabbit "in vitro" and "in vivo", have been studied. "In vitro" the TAP significantly decreased the absorption of sodium, chloride and raised the secretion of potassium, reversing the transference of bicarbonate to the secretion, both in ileum and colon. "In vivo" the T AP at ileal level had a similar effect than "in vitro", although the differences were less important. In the colon the changes were just the opposite, but they were no significative differences.Se estudia la influencia de un inhibidor de la vía paracelular 2, 4, 6 Triaminopirimidina (T AP) sobre el movimiento de agua y electrolitos en ileon distal y colon proximal de conejo "in vitro" e "in vivo". "In vitro" el TAP disminuye marcadamente la absorción de sodio, cloruro y aumenta la secreción de potasio, inviertiendo la transferencia de bicarbonato hacia la secreción. "In vivo" el T AP a nivel ileal tiene un efecto similar al indicado "in vitro", si bien las diferencias son menos importantes, mientras que a nivel de colon ocurre todo lo contrario, aunque estos cambios no son importantes

Alq mutation increases fruit set rate and allows the maintenance of fruit yield under moderate saline conditions

[EN] Arlequin (Alq) is a gain-of-function mutant whose most relevant feature is that sepals are able to become fruit-like organs due to the ectopic expression of the ALQ-TAGL1 gene. The role of this gene in tomato fruit ripening was previously demonstrated. To discover new functional roles for ALQ-TAGL1, and most particularly its involvement in the fruit set process, a detailed characterization of Alq yield-related traits was performed. Under standard conditions, the Alq mutant showed a much higher fruit set rate than the wild type. A significant percentage of Alq fruits were seedless. The results showed that pollination-independent fruit set in Alq is due to early transition from flower to fruit. Analysis of endogenous hormones in Alq suggests that increased content of cytokinins and decreased level of abscisic acid may account for precocious fruit set. Comparative expression analysis showed relevant changes of several genes involved in cell division, gibberellin metabolism, and the auxin signalling pathway. Since pollination-independent fruit set may be a very useful strategy for maintaining fruit production under adverse conditions, fruit set and yield in Alq plants under moderate salinity were assessed. Interestingly, Alq mutant plants showed a high yield under saline conditions, similar to that of Alq and the wild type under unstressed conditions.This work was supported by the research grants AGL2015-64991-C3-3-R and AGL2015-64991-C3-1-R from the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER). The PhD grant to CRA (BES-2013-063778) was funded by the Spanish Ministry of Economy and Competitiveness.The authors thank Dr Isabel Lopez-Diaz and Dr Esther Carrera for their help in hormone quantification carried out at the Plant Hormone Quantification Service, IBMCP,Valencia, Spain. The authors thank David Harry Rhead for reviewing the manuscript in the English language.Ribelles Alfonso, C.; García Sogo, B.; Yuste-Lisbona, FJ.; Atarés Huerta, A.; Castañeda, L.; Capel, C.; Lozano, R.... (2019). Alq mutation increases fruit set rate and allows the maintenance of fruit yield under moderate saline conditions. Journal of Experimental Botany. 70(20):5731-5744. https://doi.org/10.1093/jxb/erz342S57315744702

IRE1β negatively regulates IRE1α signaling in response to endoplasmic reticulum stress

IRE1β is an ER stress sensor uniquely expressed in epithelial cells lining mucosal surfaces. Here, we show that intestinal epithelial cells expressing IRE1β have an attenuated unfolded protein response to ER stress. When modeled in HEK293 cells and with purified protein, IRE1β diminishes expression and inhibits signaling by the closely related stress sensor IRE1α. IRE1β can assemble with and inhibit IRE1α to suppress stress-induced XBP1 splicing, a key mediator of the unfolded protein response. In comparison to IRE1α, IRE1β has relatively weak XBP1 splicing activity, largely explained by a nonconserved amino acid in the kinase domain active site that impairs its phosphorylation and restricts oligomerization. This enables IRE1β to act as a dominant-negative suppressor of IRE1α and affect how barrier epithelial cells manage the response to stress at the host–environment interface

The res (restored cell structure by salinity) tomato mutant reveals the role of the DEAD-box RNA helicase SlDEAD39 in plant development and salt response

[EN] Increasing evidences highlight the importance of DEAD-box RNA helicases in plant development and stress responses. In a previous study, we characterized the tomato res mutant (restored cell structure by salinity), showing chlorosis and development alterations that reverted under salt-stress conditions. Map-based cloning demonstrates that RES gene encodes SlDEAD39, a chloroplast-targeted DEAD-box RNA helicase. Constitutive expression of SlDEAD39 complements the res mutation, while the silencing lines had a similar phenotype than res mutant, which is also reverted under salinity. Functional analysis of res mutant proved SlDEAD39 is involved in the in vivo processing of the chloroplast, 23S rRNA, at the hidden break-B site, a feature also supported by in vitro binding experiments of the protein. In addition, our results show that other genes coding for chloroplast-targeted DEAD-box proteins are induced by salt-stress, which might explain the rescue of the res mutant phenotype. Interestingly, salinity restored the phenotype of res adult plants by increasing their sugar content and fruit yield. Together, these results propose an unprecedented role of a DEAD-box RNA helicase in regulating plant development and stress response through the proper ribosome and chloroplast functioning, which, in turn, represents a potential target to improve salt tolerance in tomato cropsSecretaria de Estado de Investigacion, Desarrollo e Innovacion, Grant/Award Numbers: AGL2015-64991-C3-1-R, AGL2015-64991-C3-2-R, AGL2015-64991-C3-3-R, AGL2017-88702-C2-1-RCapel, C.; Albaladejo, I.; Egea, I.; Massaretto, IL.; Yuste-Lisbona, FJ.; Pineda Chaza, BJ.; García Sogo, B.... (2020). The res (restored cell structure by salinity) tomato mutant reveals the role of the DEAD-box RNA helicase SlDEAD39 in plant development and salt response. Plant Cell & Environment. 43(7):1722-1739. https://doi.org/10.1111/pce.13776S1722173943