Future climate doubles the risk of hydraulic failure in a wet tropical forest.

Future climate presents conflicting implications for forest biomass. We evaluate how plant hydraulic traits, elevated CO2 levels, warming, and changes in precipitation affect forest primary productivity, evapotranspiration, and the risk of hydraulic failure. We used a dynamic vegetation model with plant hydrodynamics (FATES-HYDRO) to simulate the stand-level responses to future climate changes in a wet tropical forest in Barro Colorado Island, Panama. We calibrated the model by selecting plant trait assemblages that performed well against observations. These assemblages were run with temperature and precipitation changes for two greenhouse gas emission scenarios (2086-2100: SSP2-45, SSP5-85) and two CO2 levels (contemporary, anticipated). The risk of hydraulic failure is projected to increase from a contemporary rate of 5.7% to 10.1-11.3% under future climate scenarios, and, crucially, elevated CO2 provided only slight amelioration. By contrast, elevated CO2 mitigated GPP reductions. We attribute a greater variation in hydraulic failure risk to trait assemblages than to either CO2 or climate. Our results project forests with both faster growth (through productivity increases) and higher mortality rates (through increasing rates of hydraulic failure) in the neo-tropics accompanied by certain trait plant assemblages becoming nonviable.

Wood-density has no effect on stomatal control of leaf-level water use efficiency in an Amazonian forest.

Forest disturbances increase the proportion of fast-growing tree species compared to slow-growing ones. To understand their relative capacity for carbon uptake and their vulnerability to climate change, and to represent those differences in Earth system models, it is necessary to characterise the physiological differences in their leaf-level control of water use efficiency and carbon assimilation. We used wood density as a proxy for the fast-slow growth spectrum and tested the assumption that trees with a low wood density (LWD) have a lower water-use efficiency than trees with a high wood density (HWD). We selected 5 LWD tree species and 5 HWD tree species growing in the same location in an Amazonian tropical forest and measured in situ steady-state gas exchange on top-of-canopy leaves with parallel sampling and measurement of leaf mass area and leaf nitrogen content. We found that LWD species invested more nitrogen in photosynthetic capacity than HWD species, had higher photosynthetic rates and higher stomatal conductance. However, contrary to expectations, we showed that the stomatal control of the balance between transpiration and carbon assimilation was similar in LWD and HWD species and that they had the same dark respiration rates.

Treatment of cardiac device-related infective endocarditis utilizing the new T20 curve catheter and flow saver with the Inari mechanical aspiration system.

Emerging innovations have led to the development of tools and techniques to perform mechanical aspiration of right-sided endocarditis vegetations. However, blood loss during aspiration, the need for veno-veno bypass, and nonsteerable catheters have limited expansion of these treatment options to more patients. We present a case of pacemaker lead endocarditis treated with the Inari mechanical aspiration system utilizing the new T20 curved catheter (Inari Medical).

Orbital atherectomy of calcified coronary ostial lesions.

OBJECTIVES: To evaluate the feasibility and safety of coronary orbital atherectomy (OA) for the treatment of calcified ostial lesions. BACKGROUND: Percutaneous coronary intervention (PCI) is increasingly being completed in complex patients and lesions. OA is effective for severely calcified coronary lesions; however, there is a dearth of evidence on the use of OA in ostial lesions, especially with long-term outcome data. METHODS: Data were obtained from a retrospective analysis of patients who underwent OA of heavily calcified ostial lesions followed by stent implantation from December 2010 to June 2019 at two high-volume PCI centers. Kaplan-Meier analysis was utilized to assess the primary endpoints of 30-day, 1-year, and 2-year freedom-from (FF) major adverse cardiac events (MACE: death, myocardial infarction, or target vessel revascularization), stroke, and stent thrombosis (ST). RESULTS: A total of 56 patients underwent OA to treat heavily calcified ostial coronary lesions. The mean age was 72 years with a high prevalence of diabetes (55%) and heart failure (36%), requiring hemodynamic support (14%). There was high FF angiographic complications (93%), and at 30-day, 1-year, and 2-year, a high FF-MACE (96%, 91%, and 88%), stroke (98%, 96%, and 96%), and ST (100%), respectively. CONCLUSIONS: This study represents the largest real-world experience of coronary OA use in heavily calcified ostial lesions with long-term outcomes over 2 years. The main finding in this retrospective analysis is that, despite the complex patients and lesions included in this analysis, OA appears to be a feasible and safe treatment option for calcified coronary ostial lesions.

Percutaneous mechanical thrombectomy in a real-world pulmonary embolism population: Interim results of the FLASH registry.

OBJECTIVES: The FlowTriever All-Comer Registry for Patient Safety and Hemodynamics (FLASH) is a prospective multi-center registry evaluating the safety and effectiveness of percutaneous mechanical thrombectomy for treatment of pulmonary embolism (PE) in a real-world patient population (NCT03761173). This interim analysis reports outcomes for the first 250 patients enrolled in FLASH. BACKGROUND: High- and intermediate-risk PEs are characterized by high mortality rates, frequent readmissions, and long-term sequelae. Mechanical thrombectomy is emerging as a front-line therapy for PE that enables immediate thrombus reduction while avoiding the bleeding risks inherent with thrombolytics. METHODS: The primary endpoint is a composite of major adverse events (MAE) including device-related death, major bleeding, and intraprocedural device- or procedure-related adverse events at 48 h. Secondary endpoints include on-table changes in hemodynamics and longer-term measures including dyspnea, heart rate, and cardiac function. RESULTS: Patients were predominantly intermediate-risk per ESC guidelines (6.8% high-risk, 93.2% intermediate-risk). There were three MAEs (1.2%), all of which were major bleeds that resolved without sequelae, with no device-related injuries, clinical deteriorations, or deaths at 48 h. All-cause mortality was 0.4% at 30 days, with a single death that was unrelated to PE. Significant on-table improvements in hemodynamics were noted, including an average reduction in mean pulmonary artery pressure of 7.1 mmHg (22.2%, p < 0.001). Patient symptoms and cardiac function improved through follow-up. CONCLUSIONS: These interim results provide preliminary evidence of excellent safety in a real-world PE population. Reported outcomes suggest that mechanical thrombectomy can result in immediate hemodynamic improvements, symptom reduction, and cardiac function recovery.

Single-access during Impella hemodynamic support utilizing the Railway system.

A single-access technique during mechanical circulatory support (MCS) and percutaneous coronary intervention (PCI) has been described for those patients where an additional arterial access site is not available or desired. This technique utilizes the Impella (Abiomed, Danvers, MA) 14 French (F) sheath as a single-access point, with a 7 F sheath through the 14 F sheath hemostatic valve next to the Impella catheter (Abiomed). However, this technique is limited to a 7 F sheath or smaller and can be difficult requiring multiple attempts and limit guide catheter manipulation. We describe a single-access technique utilizing the Impella (Abiomed) 14 F sheath and a standard 7 F guide catheter placed sheathless through the 14 F sheath hemostatic valve utilizing the Railway Sheathless Access System (Cortis, Santa Clara, CA).

Convergent evolution of tree hydraulic traits in Amazonian habitats: implications for community assemblage and vulnerability to drought.

Amazonian droughts are increasing in frequency and severity. However, little is known about how this may influence species-specific vulnerability to drought across different ecosystem types. We measured 16 functional traits for 16 congeneric species from six families and eight genera restricted to floodplain, swamp, white-sand or plateau forests of Central Amazonia. We investigated whether habitat distributions can be explained by species hydraulic strategies, and if habitat specialists differ in their vulnerability to embolism that would make water transport difficult during drought periods. We found strong functional differences among species. Nonflooded species had higher wood specific gravity and lower stomatal density, whereas flooded species had wider vessels, and higher leaf and xylem hydraulic conductivity. The P50 values (water potential at 50% loss of hydraulic conductivity) of nonflooded species were significantly more negative than flooded species. However, we found no differences in hydraulic safety margin among species, suggesting that all trees may be equally likely to experience hydraulic failure during severe droughts. Water availability imposes a strong selection leading to differentiation of plant hydraulic strategies among species and may underlie patterns of adaptive radiation in many tropical tree genera. Our results have important implications for modeling species distribution and resilience under future climate scenarios.

Forest responses to simulated elevated CO2 under alternate hypotheses of size- and age-dependent mortality.

Elevated atmospheric carbon dioxide (eCO2 ) is predicted to increase growth rates of forest trees. The extent to which increased growth translates to changes in biomass is dependent on the turnover time of the carbon, and thus tree mortality rates. Size- or age-dependent mortality combined with increased growth rates could result in either decreased carbon turnover from a speeding up of tree life cycles, or increased biomass from trees reaching larger sizes, respectively. However, most vegetation models currently lack any representation of size- or age-dependent mortality and the effect of eCO2 on changes in biomass and carbon turnover times is thus a major source of uncertainty in predictions of future vegetation dynamics. Using a reduced-complexity form of the vegetation demographic model the Functionally Assembled Terrestrial Ecosystem Simulator to simulate an idealised tropical forest, we find increases in biomass despite reductions in carbon turnover time in both size- and age-dependent mortality scenarios in response to a hypothetical eCO2 -driven 25% increase in woody net primary productivity (wNPP). Carbon turnover times decreased by 9.6% in size-dependent mortality scenarios due to a speeding up of tree life cycles, but also by 2.0% when mortality was age-dependent, as larger crowns led to increased light competition. Increases in aboveground biomass (AGB) were much larger when mortality was age-dependent (24.3%) compared with size-dependent (13.4%) as trees reached larger sizes before death. In simulations with a constant background mortality rate, carbon turnover time decreased by 2.1% and AGB increased by 24.0%, however, absolute values of AGB and carbon turnover were higher than in either size- or age-dependent mortality scenario. The extent to which AGB increases and carbon turnover decreases will thus depend on the mechanisms of large tree mortality: if increased size itself results in elevated mortality rates, then this could reduce by about half the increase in AGB relative to the increase in wNPP.

Stimulation of isoprene emissions and electron transport rates as key mechanisms of thermal tolerance in the tropical species Vismia guianensis.

Tropical forests absorb large amounts of atmospheric CO2 through photosynthesis, but high surface temperatures suppress this absorption while promoting isoprene emissions. While mechanistic isoprene emission models predict a tight coupling to photosynthetic electron transport (ETR) as a function of temperature, direct field observations of this phenomenon are lacking in the tropics and are necessary to assess the impact of a warming climate on global isoprene emissions. Here we demonstrate that in the early successional species Vismia guianensis in the central Amazon, ETR rates increased with temperature in concert with isoprene emissions, even as stomatal conductance (gs ) and net photosynthetic carbon fixation (Pn ) declined. We observed the highest temperatures of continually increasing isoprene emissions yet reported (50°C). While Pn showed an optimum value of 32.6 ± 0.4°C, isoprene emissions, ETR, and the oxidation state of PSII reaction centers (qL ) increased with leaf temperature with strong linear correlations for ETR (Æ¿ = 0.98) and qL (Æ¿ = 0.99) with leaf isoprene emissions. In contrast, other photoprotective mechanisms, such as non-photochemical quenching, were not activated at elevated temperatures. Inhibition of isoprenoid biosynthesis repressed Pn at high temperatures through a mechanism that was independent of stomatal closure. While extreme warming will decrease gs and Pn in tropical species, our observations support a thermal tolerance mechanism where the maintenance of high photosynthetic capacity under extreme warming is assisted by the simultaneous stimulation of ETR and metabolic pathways that consume the direct products of ETR including photorespiration and the biosynthesis of thermoprotective isoprenoids. Our results confirm that models which link isoprene emissions to the rate of ETR hold true in tropical species and provide necessary "ground-truthing" for simulations of the large predicted increases in tropical isoprene emissions with climate warming.

TIME Trial: Effect of Timing of Stem Cell Delivery Following ST-Elevation Myocardial Infarction on the Recovery of Global and Regional Left Ventricular Function: Final 2-Year Analysis.

RATIONALE: The TIME trial (Timing in Myocardial Infarction Evaluation) was the first cell therapy trial sufficiently powered to determine if timing of cell delivery after ST-segment-elevation myocardial infarction affects recovery of left ventricular (LV) function. OBJECTIVE: To report the 2-year clinical and cardiac magnetic resonance imaging results and their modification by microvascular obstruction. METHODS AND RESULTS: TIME was a randomized, double-blind, placebo-controlled trial comparing 150 million bone marrow mononuclear cells versus placebo in 120 patients with anterior ST-segment-elevation myocardial infarctions resulting in LV dysfunction. Primary end points included changes in global (LV ejection fraction) and regional (infarct and border zone) function. Secondary end points included changes in LV volumes, infarct size, and major adverse cardiac events. Here, we analyzed the continued trajectory of these measures out to 2 years and the influence of microvascular obstruction present at baseline on these long-term outcomes. At 2 years (n=85), LV ejection fraction was similar in the bone marrow mononuclear cells (48.7%) and placebo groups (51.6%) with no difference in regional LV function. Infarct size and LV mass decreased ≥30% in each group at 6 months and declined gradually to 2 years. LV volumes increased ≈10% at 6 months and remained stable to 2 years. Microvascular obstruction was present in 48 patients at baseline and was associated with significantly larger infarct size (56.5 versus 36.2 g), greater adverse LV remodeling, and marked reduction in LV ejection fraction recovery (0.2% versus 6.2%). CONCLUSIONS: In one of the longest serial cardiac magnetic resonance imaging analyses of patients with large anterior ST-segment-elevation myocardial infarctions, bone marrow mononuclear cells administration did not improve recovery of LV function over 2 years. Microvascular obstruction was associated with reduced recovery of LV function, greater adverse LV remodeling, and more device implantations. The use of cardiac magnetic resonance imaging leads to greater dropout of patients over time because of device implantation in patients with more severe LV dysfunction resulting in overestimation of clinical stability of the cohort. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00684021.

MRI Evaluation of an Atrial-Anchored Transcatheter Mitral Valve Replacement Implant.

OBJECTIVE. A medical implant that is made from metal must undergo proper MRI testing to ensure patient safety. The purpose of this investigation was to assess issues with MRI with a newly developed atrial-anchored transcatheter mitral valve replacement (TMVR) implant. MATERIALS AND METHODS. The atrial-anchored TMVR implant underwent an in vitro evaluation for MRI safety issues using standardized techniques and well-accepted methods. Magnetic field interactions including translational attraction and torque and artifacts were tested at 3 T. MRI-related heating was assessed at 1.5 T/64 MHz and 3 T/128 MHz using numeric simulations with analytical modeling and experimental testing. RESULTS. The atrial-anchored TMVR implant exhibited minor magnetic field interactions (9° deflection angle and no torque) at 3 T. The findings from the numeric simulations with analytical modeling were used to guide the placement of the implant in the phantom for the heating test and to identify the position on the implant that would result in the highest temperature rise. The highest temperature elevations recorded for the TMVR implant obtained on MRI at 1.5 T/64 MHz and 3 T/128 MHz were 2.7°C and 2.4°C, respectively. The maximum artifact size seen on a gradient echo pulse sequence extended approximately 5 mm relative to the size of the implant. CONCLUSION. The results of the tests performed on the atrial-anchored TMVR implant revealed no substantial concerns with respect to the conditions used in this investigation. Therefore, a patient with this new implant can safely undergo MRI by following the specific conditions defined by this study. The implant was deemed MR Conditional.

Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale.

The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets, respectively. The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

Homoeostatic maintenance of nonstructural carbohydrates during the 2015-2016 El Niño drought across a tropical forest precipitation gradient.

Nonstructural carbohydrates (NSCs) are essential for maintenance of plant metabolism and may be sensitive to short- and long-term climatic variation. NSC variation in moist tropical forests has rarely been studied, so regulation of NSCs in these systems is poorly understood. We measured foliar and branch NSC content in 23 tree species at three sites located across a large precipitation gradient in Panama during the 2015-2016 El Niño to examine how short- and long-term climatic variation impact carbohydrate dynamics. There was no significant difference in total NSCs as the drought progressed (leaf P = 0.32, branch P = 0.30) nor across the rainfall gradient (leaf P = 0.91, branch P = 0.96). Foliar soluble sugars decreased while starch increased over the duration of the dry period, suggesting greater partitioning of NSCs to storage than metabolism or transport as drought progressed. There was a large variation across species at all sites, but total foliar NSCs were positively correlated with leaf mass per area, whereas branch sugars were positively related to leaf temperature and negatively correlated with daily photosynthesis and wood density. The NSC homoeostasis across a wide range of conditions suggests that NSCs are an allocation priority in moist tropical forests.

Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics.

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.

Variation in hydroclimate sustains tropical forest biomass and promotes functional diversity.

The fate of tropical forests under climate change is unclear as a result, in part, of the uncertainty in projected changes in precipitation and in the ability of vegetation models to capture the effects of drought-induced mortality on aboveground biomass (AGB). We evaluated the ability of a terrestrial biosphere model with demography and hydrodynamics (Ecosystem Demography, ED2-hydro) to simulate AGB and mortality of four tropical tree plant functional types (PFTs) that operate along light- and water-use axes. Model predictions were compared with observations of canopy trees at Barro Colorado Island (BCI), Panama. We then assessed the implications of eight hypothetical precipitation scenarios, including increased annual precipitation, reduced inter-annual variation, El Niño-related droughts and drier wet or dry seasons, on AGB and functional diversity of the model forest. When forced with observed meteorology, ED2-hydro predictions capture multiple BCI benchmarks. ED2-hydro predicts that AGB will be sustained under lower rainfall via shifts in the functional composition of the forest, except under the drier dry-season scenario. These results support the hypothesis that inter-annual variation in mean and seasonal precipitation promotes the coexistence of functionally diverse PFTs because of the relative differences in mortality rates. If the hydroclimate becomes chronically drier or wetter, functional evenness related to drought tolerance may decline.

Windthrows control biomass patterns and functional composition of Amazon forests.

Amazon forests account for ~25% of global land biomass and tropical tree species. In these forests, windthrows (i.e., snapped and uprooted trees) are a major natural disturbance, but the rates and mechanisms of recovery are not known. To provide a predictive framework for understanding the effects of windthrows on forest structure and functional composition (DBH ≥10 cm), we quantified biomass recovery as a function of windthrow severity (i.e., fraction of windthrow tree mortality on Landsat pixels, ranging from 0%-70%) and time since disturbance for terra-firme forests in the Central Amazon. Forest monitoring allowed insights into the processes and mechanisms driving the net biomass change (i.e., increment minus loss) and shifts in functional composition. Windthrown areas recovering for between 4-27 years had biomass stocks as low as 65.2-91.7 Mg/ha or 23%-38% of those in nearby undisturbed forests (~255.6 Mg/ha, all sites). Even low windthrow severities (4%-20% tree mortality) caused decadal changes in biomass stocks and structure. While rates of biomass increment in recovering vegetation were nearly double (6.3 ± 1.4 Mg ha-1  year-1 ) those of undisturbed forests (~3.7 Mg ha-1  year-1 ), biomass loss due to post-windthrow mortality was high (up to -7.5 ± 8.7 Mg ha-1  year-1 , 8.5 years since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40 years. Resprouting trees contributed little to biomass recovery. Instead, light-demanding, low-density genera (e.g., Cecropia, Inga, Miconia, Pourouma, Tachigali, and Tapirira) were favored, resulting in substantial post-windthrow species turnover. Shifts in functional composition demonstrate that windthrows affect the resilience of live tree biomass by favoring soft-wooded species with shorter life spans that are more vulnerable to future disturbances. As the time required for forests to recover biomass is likely similar to the recurrence interval of windthrows triggering succession, windthrows have the potential to control landscape biomass/carbon dynamics and functional composition in Amazon forests.

Impact of diabetes mellitus on procedural and one year clinical outcomes following treatment of severely calcified coronary lesions with the orbital atherectomy system: A subanalysis of the ORBIT II study.

OBJECTIVES: The goal of the study was to investigate the safety and efficacy of the coronary orbital atherectomy system to treat severe coronary artery calcification (CAC) prior to stent placement in diabetic and non-diabetic patients. BACKGROUND: The ORBIT II study reported the safety and efficacy of orbital atherectomy treatment in 443 patients with severe CAC. Percutaneous coronary intervention in diabetic patients is associated with an increased risk of major adverse cardiac events (MACE) compared with non-diabetics. The outcomes of diabetic patients who undergo orbital atherectomy are unknown. METHODS: Patients were sub-grouped as either diabetic (160/443, 36.1%) or non-diabetic (283/443, 63.9%). The MACE rate, defined as cardiac death, myocardial infarction (MI; CK-MB > 3X ULN), and target vessel revascularization, was examined at 30 days and 1 year after treatment. RESULTS: Procedural success was similar in the diabetic and non-diabetic groups (89.3 vs. 88.6%, P = 0.88). There was no significant difference in the 30-day and 1-year MACE rates between the diabetic and non-diabetic groups (30 day: 8.8 vs. 11.3%; P = 0.40; 1 year: 17.1 vs. 16.7%, P = 0.97). The individual components of cardiac death (3.9 vs. 2.9%, P = 0.58), MI (9.4 vs. 11.3%, P = 0.52), and target vessel revascularization (5.9 vs. 5.8%, P = 0.99) were also similar in both groups at 1 year. CONCLUSIONS: The rates of adverse clinical events in diabetic patients who underwent orbital atherectomy were low and similar to non-diabetic patients. This study suggests orbital atherectomy is a reasonable treatment strategy for diabetic patients with severe CAC.

Below versus above Ground Plant Sources of Abscisic Acid (ABA) at the Heart of Tropical Forest Response to Warming.

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios.

Monoterpene 'thermometer' of tropical forest-atmosphere response to climate warming.

Tropical forests absorb large amounts of atmospheric CO2 through photosynthesis but elevated temperatures suppress this absorption and promote monoterpene emissions. Using 13 CO2 labeling, here we show that monoterpene emissions from tropical leaves derive from recent photosynthesis and demonstrate distinct temperature optima for five groups (Groups 1-5), potentially corresponding to different enzymatic temperature-dependent reaction mechanisms within ß-ocimene synthases. As diurnal and seasonal leaf temperatures increased during the Amazonian 2015 El Niño event, leaf and landscape monoterpene emissions showed strong linear enrichments of ß-ocimenes (+4.4% °C-1 ) at the expense of other monoterpene isomers. The observed inverse temperature response of α-pinene (-0.8% °C-1 ), typically assumed to be the dominant monoterpene with moderate reactivity, was not accurately simulated by current global emission models. Given that ß-ocimenes are highly reactive with respect to both atmospheric and biological oxidants, the results suggest that highly reactive ß-ocimenes may play important roles in the thermotolerance of photosynthesis by functioning as effective antioxidants within plants and as efficient atmospheric precursors of secondary organic aerosols. Thus, monoterpene composition may represent a new sensitive 'thermometer' of leaf oxidative stress and atmospheric reactivity, and therefore a new tool in future studies of warming impacts on tropical biosphere-atmosphere carbon-cycle feedbacks.

ORBIT II sub-analysis: Impact of impaired renal function following treatment of severely calcified coronary lesions with the Orbital Atherectomy System.

OBJECTIVES: To investigate the safety and efficacy of the coronary Orbital Atherectomy System (OAS) to prepare severely calcified lesions for stent deployment in patients grouped by renal function. BACKGROUND: Percutaneous coronary intervention (PCI) of severely calcified lesions is associated with increased rates of major adverse cardiac events (MACE), including death, myocardial infarction (MI), and target vessel revascularization (TVR) compared with PCI of non-calcified vessels. Patients with chronic kidney disease (CKD) are at increased risk for MACE after PCI. The impact of CKD on coronary orbital atherectomy treatment has not been well characterized. METHODS: ORBIT II was a prospective, multicenter trial in the U.S., which enrolled 443 patients with severely calcified coronary lesions. The MACE rate was defined as a composite of cardiac death, MI, and target vessel revascularization. RESULTS: Of the 441 patients enrolled with known estimated glomerular filtration rate (eGFR) values at baseline, 333 (75.5%) patients had eGFR < 90 ml/min/1.73 m2 and 108 patients had eGFR ≥ 90 ml/min/1.73 m2 . The mean eGFR at baseline in the eGFR < 90 ml/min/1.73 m2 and eGFR ≥ 90 ml/min/1.73 m2 groups was 65.0 ± 0.9 ml/min/1.73 m2 and 109.1 ± 2.0 ml/min/1.73 m2 , respectively. Freedom from MACE was lower in the eGFR < 90 ml/min/1.73 m2 group at 30 days (87.4% vs. 96.3%, P = 0.02) and 1-year (80.6% vs. 90.7%, P = 0.02). CONCLUSIONS: Patients with renal impairment had a higher MACE rate through one year follow-up due to a higher rate of periprocedural MI. Interestingly, the rates of cardiac death and revascularization through 1-year were similar in patients with eGFR < 90 ml/min/1.73 m2 and eGFR ≥ 90 ml/min/1.73 m2 . Future studies are needed to identify the ideal revascularization strategy for patients with renal impairment and severely calcified coronary lesions. © 2016 Wiley Periodicals, Inc.