Alzheimer’s disease-associated peptide Aβ₄₂ mobilizes ER Ca²⁺ via InsP₃R-dependent and -independent mechanisms

Dysregulation of Ca2+ homeostasis is considered to contribute to the toxic action of the Alzheimer’s Disease (AD) associated Amyloid β-peptide (Aβ). Ca2+ fluxes across the plasma membrane and release from intracellular stores have both been reported to underlie the Ca2+ fluxes induced by Aβ42. Here, we investigated the contribution of Ca2+ release from the endoplasmic reticulum (ER) to the effects of Aβ42 upon Ca2+ homeostasis and the mechanism by which Aβ42 elicited these effects. Consistent with previous reports, application of soluble oligomeric forms of Aβ42 exhibited Ca2+ mobilizing properties. The Aβ42-stimulated Ca2+ signals persisted in the absence of extracellular Ca2+ indicating a significant contribution of Ca2+ release from the ER Ca2+ store to the generation of these signals. Moreover, inositol 1,4,5-trisphosphate (InsP3) signaling contributed to Aβ42-stimulated Ca2+ release. The Ca2+ mobilizing effect of Aβ42 was also observed when applied to permeabilized cells deficient in InsP3 receptors revealing an additional direct effect of internalized Aβ42 upon the ER, and a mechanism for induction of toxicity by intracellular Aβ42

Design of a pulse generator for testing partial discharge measurement systems

This paper deals with the design and implementation of a pulse generator serving as a reference generator for setting up measuring systems for monitoring partial discharges (PD) in high-voltage power transformers or gas insulated switchgear (GIS). After installing the measuring device, it is advisable to test the entire measuring chain and, if necessary, set parameters that would validate the correct detection of PD signals. Fast pulse generators are important for this verification. In systems that sense the electromagnetic activity of PD. The proposed generator should serve as the output stage of a programmable generator, which did not reach sufficient parameters for output pulses. The goal was to achieve a rising time around 100 ps and an amplitude of more than 6 V using very fast operational amplifiers and step recovery diodes to sharpen the input pulse. The measurements show waveforms of the output voltage pulse to evaluate its performance

Higher host-plant specialization of root-associated endophytes than mycorrhizal fungi along an arctic elevational gradient

How community-level specialization differs among groups of organisms, and changes along environmental gradients, is fundamental to understanding the mechanisms influencing ecological communities. In this paper, we investigate the specialization of root-associated fungi for plant species, asking whether the level of specialization varies with elevation. For this, we applied DNA barcoding based on the ITS region to root samples of five plant species equivalently sampled along an elevational gradient at a high arctic site. To assess whether the level of specialization changed with elevation and whether the observed patterns varied between mycorrhizal and endophytic fungi, we applied a joint species distribution modeling approach. Our results show that host plant specialization is not environmentally constrained in arctic root-associated fungal communities, since there was no evidence for changing specialization with elevation, even if the composition of root-associated fungal communities changed substantially. However, the level of specialization for particular plant species differed among fungal groups, root-associated endophytic fungal communities being highly specialized on particular host species, and mycorrhizal fungi showing almost no signs of specialization. Our results suggest that plant identity affects associated mycorrhizal and endophytic fungi differently, highlighting the need of considering both endophytic and mycorrhizal fungi when studying specialization in root-associated fungal communities.Peer reviewe

Seasonal temperature trends on the Spanish mainland: A secular study (1916–2015)

Trends in seasonal mean values of maximum and minimum temperature are analysed in the Spanish mainland from the new MOTEDAS_century database. This new data set has been developed combining the digitalized archives from the Spanish Meteorological Agency (AEMET) with information retrieved from Annual Books published by the former Meteorological Agency dating back to 1916, and covers the period 1916–2015. In all four seasons, mean seasonal temperature of maximum (Tmax) and minimum (Tmin) increased. The raising occurred in two main pulses separated by a first pause around the middle of the 20th century, but differed among seasons and also between maximum and minimum temperature. Analysis of the percentage of land affected by significant trends in maximum temperature reveals two increasing phases in spring and summer for Tmax, and in spring, summer, and autumn for Tmin. However, winter Tmax only rose during the recent decades, and autumn Tmax in the first decades. Negative significant trends were found in extended areas in spring Tmax, and in spring, autumn, and summer Tmin, confirming the first pause around the 1940's–1960's. Trends of seasonal mean values of Tmax and Tmin are not significant for at least the last 25–35 years of the study period, depending on the season. The areas under significant positive trend are usually more extended for Tmin than Tmax at any season and period. Areas with significant trend expand and contract in time according to two spatial gradients: south-east to north-west (east-west) for Tmax, and west to east for Tmin. We hypothesize a relationship between atmospheric prevalent advection and relief as triggering factors to understand spatial and temporal differences in seasonal temperatures at regional scale during the 20th century in the Iberian Peninsula

Higher host-plant specialization of root-associated endophytes than mycorrhizal fungi along an arctic elevational gradient

How community-level specialization differs among groups of organisms, and changes along environmental gradients, is fundamental to understanding the mechanisms influencing ecological communities. In this paper, we investigate the specialization of root-associated fungi for plant species, asking whether the level of specialization varies with elevation. For this, we applied DNA barcoding based on the ITS region to root samples of five plant species equivalently sampled along an elevational gradient at a high arctic site. To assess whether the level of specialization changed with elevation and whether the observed patterns varied between mycorrhizal and endophytic fungi, we applied a joint species distribution modeling approach. Our results show that host plant specialization is not environmentally constrained in arctic root-associated fungal communities, since there was no evidence for changing specialization with elevation, even if the composition of root-associated fungal communities changed substantially. However, the level of specialization for particular plant species differed among fungal groups, root-associated endophytic fungal communities being highly specialized on particular host species, and mycorrhizal fungi showing almost no signs of specialization. Our results suggest that plant identity affects associated mycorrhizal and endophytic fungi differently, highlighting the need of considering both endophytic and mycorrhizal fungi when studying specialization in root-associated fungal communities.Peer reviewe

Preoperative prediction of spinal cord ischemia after thoracic endovascular aortic repair

ObjectiveSpinal cord ischemia (SCI) is a devastating but potentially preventable complication of thoracic endovascular aortic repair (TEVAR). The purpose of this analysis was to determine what factors predict SCI after TEVAR.MethodsAll TEVAR procedures at a single institution were reviewed for patient characteristics, prior aortic repair history, aortic centerline of flow analysis, and procedural characteristics. SCI was defined as any lower extremity neurologic deficit that was not attributable to an intracranial process or peripheral neuropathy. Forty-three patient and procedural variables were evaluated individually for association with SCI. Those with the strongest relationships to SCI (P < .1) were included in a multivariable logistic regression model, and a stepwise variable elimination algorithm was bootstrapped to derive a best subset of predictors from this model.ResultsFrom 2002 to 2013, 741 patients underwent TEVAR for various indications, and 68 (9.2%) developed SCI (permanent: n = 38; 5.1%). Because of the lack of adequate imaging for centerline analysis, 586 patients (any SCI, n = 43; 7.4%) were subsequently analyzed. Patients experiencing SCI after TEVAR were older (SCI, 72 ± 11 years; no SCI, 65 ± 15 years; P < .0001) and had significantly higher rates of multiple cardiovascular risk factors. The stepwise selection procedure identified five variables as the most important predictors of SCI: age (odds ratio [OR] multiplies by 1.3 per 10 years; 95% confidence interval [CI], 0.9-1.8, P = .06), aortic coverage length (OR multiplies by 1.3 per 5 cm; CI, 1.1-1.6; P = .002), chronic obstructive pulmonary disease (OR, 1.9; CI, 0.9-4.1; P = .1), chronic renal insufficiency (creatinine concentration ≥ 1.6 mg/dL; OR, 1.9; CI, 0.8-4.2; P = .1), and hypertension (defined as chart history or medication; OR, 6.4; CI, 2.6-18; P < .0001). A logistic regression model with just these five covariates had excellent discrimination (area under the receiver operating characteristic curve = .83) and calibration (χ2 = 9.8; P = .28).ConclusionsThis analysis generated a simple model that reliably predicts SCI after TEVAR. This clinical tool can assist decision-making about when to proceed with TEVAR, guide discussions about intervention risk, and help determine when maneuvers to mitigate SCI risk should be implemented