PSInet: a new global water potential network.

Given the pressing challenges posed by climate change, it is crucial to develop a deeper understanding of the impacts of escalating drought and heat stress on terrestrial ecosystems and the vital services they offer. Soil and plant water potential play a pivotal role in governing the dynamics of water within ecosystems and exert direct control over plant function and mortality risk during periods of ecological stress. However, existing observations of water potential suffer from significant limitations, including their sporadic and discontinuous nature, inconsistent representation of relevant spatio-temporal scales and numerous methodological challenges.

Hydraulic variability of tropical forests is largely independent of water availability.

Tropical rainforest woody plants have been thought to have uniformly low resistance to hydraulic failure and to function near the edge of their hydraulic safety margin (HSM), making these ecosystems vulnerable to drought; however, this may not be the case. Using data collected at 30 tropical forest sites for three key traits associated with drought tolerance, we show that site-level hydraulic diversity of leaf turgor loss point, resistance to embolism (P ), and HSMs is high across tropical forests and largely independent of water availability. Species with high HSMs (>1 MPa) and low P values (< -2 MPa) are common across the wet and dry tropics.

Fire intensity impacts on physiological performance and mortality in Pinus monticola and Pseudotsuga menziesii saplings: a dose-response analysis.

Fire is a major cause of tree injury and mortality worldwide, yet our current understanding of fire effects is largely based on ocular estimates of stem charring and foliage discoloration, which are error prone and provide little information on underlying tree function. Accurate quantification of physiological performance is a research and forest management need, given that declining performance could help identify mechanisms of-and serve as an early warning sign for-mortality. Many previous efforts have been hampered by the inability to quantify the heat flux that a tree experiences during a fire, given its highly variable nature in space and time.

Death from hunger or thirst? Phloem death, rather than xylem hydraulic failure, as a driver of fire-induced conifer mortality.

Disruption of photosynthesis and carbon transport due to damage to the tree crown and stem cambial cells, respectively, can cause tree mortality. It has recently been proposed that fire-induced dysfunction of xylem plays an important role in tree mortality. Here, we simultaneously tested the impact of a lethal fire dose on nonstructural carbohydrates (NSCs) and xylem hydraulics in Pinus ponderosa saplings.

Catastrophic hydraulic failure and tipping points in plants.

Water inside plants forms a continuous chain from water in soils to the water evaporating from leaf surfaces. Failures in this chain result in reduced transpiration and photosynthesis and are caused by soil drying and/or cavitation-induced xylem embolism. Xylem embolism and plant hydraulic failure share several analogies to 'catastrophe theory' in dynamical systems.

Increased atrial effectiveness of flecainide conferred by altered biophysical properties of sodium channels.

Atrial fibrillation (AF) affects over 1% of the population and is a leading cause of stroke and heart failure in the elderly. A feared side effect of sodium channel blocker therapy, ventricular pro-arrhythmia, appears to be relatively rare in patients with AF. The biophysical reasons for this relative safety of sodium blockers are not known.

The xylem of anisohydric Quercus alba L. is more vulnerable to embolism than isohydric codominants.

The coordination of plant leaf water potential (Ψ ) regulation and xylem vulnerability to embolism is fundamental for understanding the tradeoffs between carbon uptake and risk of hydraulic damage. There is a general consensus that trees with vulnerable xylem more conservatively regulate Ψ than plants with resistant xylem. We evaluated if this paradigm applied to three important eastern US temperate tree species, Quercus alba L.

The three-dimensional construction of leaves is coordinated with water use efficiency in conifers.

Conifers prevail in the canopies of many terrestrial biomes, holding a great ecological and economic importance globally. Current increases in temperature and aridity are imposing high transpirational demands and resulting in conifer mortality. Therefore, identifying leaf structural determinants of water use efficiency is essential for predicting physiological impacts due to environmental variation.

The roles of conduit redundancy and connectivity in xylem hydraulic functions.

Wood anatomical traits shape a xylem segment's hydraulic efficiency and resistance to embolism spread due to declining water potential. It has been known for decades that variations in conduit connectivity play a role in altering xylem hydraulics. However, evaluating the precise effect of conduit connectivity has been elusive.

Neurological complications during veno-venous extracorporeal membrane oxygenation: Does the configuration matter? A retrospective analysis of the ELSO database.

Background: Single- (SL) and double-lumen (DL) catheters are used in clinical practice for veno-venous extracorporeal membrane oxygenation (V-V ECMO) therapy. However, information is lacking regarding the effects of the cannulation on neurological complications.

Methods: A retrospective observational study based on data from the Extracorporeal Life Support Organization (ELSO) registry.

Aquaporins, and not changes in root structure, provide new insights into physiological responses to drought, flooding, and salinity.

The influence of aquaporin (AQP) activity on plant water movement remains unclear, especially in plants subject to unfavorable conditions. We applied a multitiered approach at a range of plant scales to (i) characterize the resistances controlling water transport under drought, flooding, and flooding plus salinity conditions; (ii) quantify the respective effects of AQP activity and xylem structure on root (Kroot), stem (Kstem), and leaf (Kleaf) conductances; and (iii) evaluate the impact of AQP-regulated transport capacity on gas exchange. We found that drought, flooding, and flooding plus salinity reduced Kroot and root AQP activity in Pinus taeda, whereas Kroot of the flood-tolerant Taxodium distichum did not decline under flooding.

Differences in leaf anatomy determines temperature response of leaf hydraulic and mesophyll CO conductance in phylogenetically related C and C grass species.

Leaf hydraulic and mesophyll CO conductance are both influenced by leaf anatomical traits, however it is poorly understood how the temperature response of these conductances differs between C and C species with distinct leaf anatomy. This study investigated the temperature response of leaf hydraulic conductance (K ), stomatal (g ) and mesophyll (g ) conductance to CO , and leaf anatomical traits in phylogenetically related Panicum antidotale (C ) and P. bisulcatum (C ) grasses.

A thin line between life and death: Radial sap flux failure signals trajectory to tree mortality.

This article comments on: Seeking the "point of no return" in the sequence of events leading to mortality of mature trees.

Short- and long-term effects of fire on stem hydraulics in Pinus ponderosa saplings.

Understanding tree physiological responses to fire is needed to accurately model post-fire carbon processes and inform management decisions. Given trees can die immediately or at extended time periods after fire, we combined two experiments to assess the short- (one-day) and long-term (21-months) fire effects on Pinus ponderosa sapling water transport. Native percentage loss of conductivity (nPLC), vulnerability to cavitation and xylem anatomy were assessed in unburned and burned saplings at lethal and non-lethal fire intensities.

Anatomical and hydraulic responses to desiccation in emergent conifer seedlings.

Premise: The young seedling life stage is critical for reforestation after disturbance and for species migration under climate change, yet little is known regarding their basic hydraulic function or vulnerability to drought. Here, we sought to characterize responses to desiccation including hydraulic vulnerability, xylem anatomical traits, and impacts on other stem tissues that contribute to hydraulic functioning.

Methods: Larix occidentalis, Pseudotsuga menziesii, and Pinus ponderosa (all ≤6 weeks old) were imaged using x-ray computed microtomography during desiccation to assess seedling biomechanical responses with concurrently measured hydraulic conductivity (k ) and water potential (Ψ) to assess vulnerability to xylem embolism formation and other tissue damage.

Papillary muscle intervention vs mitral ring annuloplasty in ischemic mitral regurgitation.

Background And Aims: The main pathophysiological factor of chronic ischemic mitral regurgitation (MR) is the outward displacement of the papillary muscles (PMs) leading to leaflet tethering. For this reason, papillary muscle intervention (PMI) in combination with mitral ring annuloplasty (MRA) has recently been introduced into clinical practice to correct this displacement, and to reduce the recurrence of regurgitation.

Methods: A meta-analysis was conducted comparing the outcomes of PMI and MRA performed in combination vs MRA performed alone, in terms of MR recurrence and left ventricular reverse remodeling (LVRR).

Altered adrenergic response in myocytes bordering a chronic myocardial infarction underlies in vivo triggered activity and repolarization instability.

Key Points: Ventricular arrhythmias are a major complication after myocardial infarction (MI), associated with sympathetic activation. The structurally heterogeneous peri-infarct zone is a known substrate, but the functional role of the myocytes is less well known. Recordings of monophasic action potentials in vivo reveal that the peri-infarct zone is a source of delayed afterdepolarizations (DADs) and has a high beat-to-beat variability of repolarization (BVR) during adrenergic stimulation (isoproterenol, ISO).

Temporal irregularity quantification and mapping of optical action potentials using wave morphology similarity.

Background: Cardiac optical mapping enables direct and high spatio-temporal resolution recording of action potential (AP) morphology. Temporal alterations in AP morphology are both predictive and consequent of arrhythmia. Here we sought to test if methods that quantify regularity of recorded waveforms could be applied to detect and quantify periods of temporal instability in optical mapping datasets in a semi-automated, user-unbiased manner.

Six co-occurring conifer species in northern Idaho exhibit a continuum of hydraulic strategies during an extreme drought year.

As growing seasons in the northwestern USA lengthen, on track with climate predictions, the mixed conifer forests that dominate this region will experience extended seasonal drought conditions. The year of 2015, which had the most extreme drought for the area on record, offered a potential analogue of future conditions. During this period, we measured the daily courses of water potential and gas exchange as well as the hydraulic conductivity and vulnerability to embolism of six dominant native conifer species, , , , , and , to determine their responses to 5 months of record-low precipitation.

Comparison between three different equations for the estimation of glomerular filtration rate in predicting mortality after coronary artery bypass.

Background: This study was undertaken to compare the accuracy of chronic kidney disease-epidemiology collaboration (eGFR) to modification of diet in renal disease (eGFR) and the Cockcroft-Gault formulas of Creatinine clearance (C) equations in predicting post coronary artery bypass grafting (CABG) mortality.

Methods: Data from 4408 patients who underwent isolated CABG over a 11-year period were retrieved from one institutional database. Discriminatory power was assessed using the c-index and comparison between the scores' performance was performed with DeLong, bootstrap, and Venkatraman methods.

Lymphadenectomy during pulmonary metastasectomy: Impact on survival and recurrence.

Background And Objectives: Lymphadenectomy during pulmonary metastasectomy (PM) is widely carried out. We assessed the potential benefit on patient survival and tumor recurrence of this practice.

Methods: One hundred eighty-one patients undergoing a first PM were studied.

A dynamic yet vulnerable pipeline: Integration and coordination of hydraulic traits across whole plants.

The vast majority of measurements in the field of plant hydraulics have been on small-diameter branches from woody species. These measurements have provided considerable insight into plant functioning, but our understanding of plant physiology and ecology would benefit from a broader view, because branch hydraulic properties are influenced by many factors. Here, we discuss the influence that other components of the hydraulic network have on branch vulnerability to embolism propagation.