Stomatal conductance reduction tradeoffs in maize leaves: A theoretical study.

As the leading global grain crop, maize significantly impacts agricultural water usage. Presently, photosynthesis ( A net ${A}_{\text{net}}$ ) in leaves of modern maize crops is saturated with CO 2 ${\text{CO}}_{2}$ , implying that reducing stomatal conductance ( g s ${g}_{{\rm{s}}}$ ) would not affect A net ${A}_{\text{net}}$ but reduce transpiration ( τ $\tau $ ), thereby increasing water use efficiency (WUE). While g s ${g}_{{\rm{s}}}$ reduction benefits upper canopy leaves under optimal conditions, the tradeoffs in low light and nitrogen-deficient leaves under nonoptimal microenvironments remain unexplored. Moreover, g s ${g}_{{\rm{s}}}$ reduction increases leaf temperature ( T leaf ${T}_{\text{leaf}}$ ) and water vapor pressure deficit, partially counteracting transpiratory water savings. Therefore, the overall impact of g s ${g}_{{\rm{s}}}$ reduction on water savings remains unclear. Here, we use a process-based leaf model to investigate the benefits of reduced g s ${g}_{{\rm{s}}}$ in maize leaves under different microenvironments. Our findings show that increases in T leaf ${T}_{\text{leaf}}$ due to g s ${g}_{{\rm{s}}}$ reduction can diminish WUE gains by up to 20%. However, g s ${g}_{{\rm{s}}}$ reduction still results in beneficial WUE tradeoffs, where a 29% decrease in g s ${g}_{{\rm{s}}}$ in upper canopy leaves results in a 28% WUE gain without loss in A net ${A}_{\text{net}}$ . Lower canopy leaves exhibit superior tradeoffs in g s ${g}_{{\rm{s}}}$ reduction with 178% gains in WUE without loss in A net ${A}_{\text{net}}$ . Our simulations show that these WUE benefits are resilient to climate change.

Improved Domenico solution for three-dimensional contaminant transport.

The Domenico solution is a widely used analytical solution in screening tools such as BioScreen, FATE5, BioChlor, ART3D, ArcNLET, Quick-Domenico, etc., to simulate the three-dimensional transport of reactive contaminants in groundwater. While being approximate, this solution presents a convenient closed-form expression for computing plume contaminant concentrations without the need for numerical integration. Previous studies have mathematically shown that the Domenico solution provides correct estimates of contaminant plume concentrations when the value of longitudinal dispersivity is zero. However, under non-zero longitudinal dispersivity values, the errors in the Domenico solution increase, especially at plume locations beyond the advective front. The nature of these errors places severe limitations on the applicability of the Domenico solution in simulating realistic contaminant transport problems. Here, we present a new closed-form solution for three-dimensional (3D) reactive contaminant transport that overcomes this limitation. We introduce the concept of characteristic residence time, which represents the average time taken by a contaminant particle to reach a given (x, y, z) location. We show that along the plume centerline, the characteristic residence time exhibits three features, (i) initial linear response with a slope equal to the inverse of advection velocity, (ii) final saturation response with a maximum value of simulation time (iii) transition between the initial and final responses at the region surrounding the advective front, with sharper transitions at lower longitudinal dispersivities and smoother transitions at higher longitudinal dispersivities. We calibrate the Ramberg-Osgood function to fit the behavior of the characteristic residence time along the plume centerline and use this to develop a new and improved closed-form approximation for the Domenico solution. Without any additional computational effort, our new and improved solution better approximates the solute concentrations of a three-dimensional contaminant plume under realistic values of longitudinal dispersivity. Our improved solution closely matches the exact analytical solution, especially at plume locations beyond the advective front, where the Domenico solution performs poorly. Existing screening tools can be readily be retrofitted with the new and improved solution to provide more accurate estimates for plume concentrations.

Decomposition analysis on soybean productivity increase under elevated CO2 using 3-D canopy model reveals synergestic effects of CO2 and light in photosynthesis.

BACKGROUND AND AIMS: Understanding how climate change influences crop productivity helps in identifying new options to increase crop productivity. Soybean is the most important dicotyledonous seed crop in terms of planting area. Although the impacts of elevated atmospheric [CO2] on soybean physiology, growth and biomass accumulation have been studied extensively, the contribution of different factors to changes in season-long whole crop photosynthetic CO2 uptake [gross primary productivity (GPP)] under elevated [CO2] have not been fully quantified. METHODS: A 3-D canopy model combining canopy 3-D architecture, ray tracing and leaf photosynthesis was built to: (1) study the impacts of elevated [CO2] on soybean GPP across a whole growing season; (2) dissect the contribution of different factors to changes in GPP; and (3) determine the extent, if any, of synergism between [CO2] and light on changes in GPP. The model was parameterized from measurements of leaf physiology and canopy architectural parameters at the soybean Free Air CO2 Enrichment (SoyFACE) facility in Champaign, Illinois. KEY RESULTS: Using this model, we showed that both a CO2 fertilization effect and changes in canopy architecture contributed to the large increase in GPP while acclimation in photosynthetic physiological parameters to elevated [CO2] and altered leaf temperature played only a minor role in the changes in GPP. Furthermore, at early developmental stages, elevated [CO2] increased leaf area index which led to increased canopy light absorption and canopy photosynthesis. At later developmental stages, on days with high ambient light levels, the proportion of leaves in a canopy limited by Rubisco carboxylation increased from 12.2 % to 35.6 %, which led to a greater enhancement of elevated [CO2] to GPP. CONCLUSIONS: This study develops a new method to dissect the contribution of different factors to responses of crops under climate change. We showed that there is a synergestic effect of CO2 and light on crop growth under elevated CO2 conditions.

Vitamin D deficiency and degree of coronary artery luminal stenosis in women undergoing coronary angiography: a prospective observational study.

BACKGROUND AND AIMS: Low serum 25-OH D levels are associated with increased cardiovascular morbidity and mortality. Recent studies have linked 25-OH D deficiency with the presence of CAD. Women, especially post-menopausal, tend to suffer from accelerated atherosclerosis, along with vitamin D deficiency. In the present study we sought to investigate whether there is a direct association of coronary artery luminal stenosis with 25-OH D deficiency in women. PATIENTS AND METHODS: We enrolled women aged >40 who were scheduled to undergo elective coronary angiography between 3/2011 and 10/2016 in a prospective observational study. RESULTS: We included a total of 105 women. Patients had hypertension (73%), hyperlipidemia (54%), diabetes (29%), smoking (31%), family history of CAD (62%), and known CAD (21%). Median 25-OH D levels were 15.8 ng/mL (range, 3.9-79). Patients had left-anterior descending (31%), left circumflex (22%), and right coronary artery disease (26%); 27% had 2-vessel and 11% had 3-vessel disease. There was a significant inverse correlation between 25-OH D levels and the degree of maximum luminal stenosis. The burden of CAD increased across categories of worsening 25-OH D deficiency. CONCLUSIONS: Vitamin D deficiency is associated with the degree of luminal stenosis and burden of CAD in women undergoing coronary angiography. Future studies should investigate if the repletion of 25-OH D impacts the progression of CAD and cardiovascular mortality.

Use of computational modeling combined with advanced visualization to develop strategies for the design of crop ideotypes to address food security.

Sustainable crop production is a contributing factor to current and future food security. Innovative technologies are needed to design strategies that will achieve higher crop yields on less land and with fewer resources. Computational modeling coupled with advanced scientific visualization enables researchers to explore and interact with complex agriculture, nutrition, and climate data to predict how crops will respond to untested environments. These virtual observations and predictions can direct the development of crop ideotypes designed to meet future yield and nutritional demands. This review surveys modeling strategies for the development of crop ideotypes and scientific visualization technologies that have led to discoveries in "big data" analysis. Combined modeling and visualization approaches have been used to realistically simulate crops and to guide selection that immediately enhances crop quantity and quality under challenging environmental conditions. This survey of current and developing technologies indicates that integrative modeling and advanced scientific visualization may help overcome challenges in agriculture and nutrition data as large-scale and multidimensional data become available in these fields.

Crops In Silico: Generating Virtual Crops Using an Integrative and Multi-scale Modeling Platform.

Multi-scale models can facilitate whole plant simulations by linking gene networks, protein synthesis, metabolic pathways, physiology, and growth. Whole plant models can be further integrated with ecosystem, weather, and climate models to predict how various interactions respond to environmental perturbations. These models have the potential to fill in missing mechanistic details and generate new hypotheses to prioritize directed engineering efforts. Outcomes will potentially accelerate improvement of crop yield, sustainability, and increase future food security. It is time for a paradigm shift in plant modeling, from largely isolated efforts to a connected community that takes advantage of advances in high performance computing and mechanistic understanding of plant processes. Tools for guiding future crop breeding and engineering, understanding the implications of discoveries at the molecular level for whole plant behavior, and improved prediction of plant and ecosystem responses to the environment are urgently needed. The purpose of this perspective is to introduce Crops in silico (cropsinsilico.org), an integrative and multi-scale modeling platform, as one solution that combines isolated modeling efforts toward the generation of virtual crops, which is open and accessible to the entire plant biology community. The major challenges involved both in the development and deployment of a shared, multi-scale modeling platform, which are summarized in this prospectus, were recently identified during the first Crops in silico Symposium and Workshop.

Decreasing, not increasing, leaf area will raise crop yields under global atmospheric change.

Without new innovations, present rates of increase in yields of food crops globally are inadequate to meet the projected rising food demand for 2050 and beyond. A prevailing response of crops to rising [CO2 ] is an increase in leaf area. This is especially marked in soybean, the world's fourth largest food crop in terms of seed production, and the most important vegetable protein source. Is this increase in leaf area beneficial, with respect to increasing yield, or is it detrimental? It is shown from theory and experiment using open-air whole-season elevation of atmospheric [CO2 ] that it is detrimental not only under future conditions of elevated [CO2 ] but also under today's [CO2 ]. A mechanistic biophysical and biochemical model of canopy carbon exchange and microclimate (MLCan) was parameterized for a modern US Midwest soybean cultivar. Model simulations showed that soybean crops grown under current and elevated (550 [ppm]) [CO2 ] overinvest in leaves, and this is predicted to decrease productivity and seed yield 8% and 10%, respectively. This prediction was tested in replicated field trials in which a proportion of emerging leaves was removed prior to expansion, so lowering investment in leaves. The experiment was conducted under open-air conditions for current and future elevated [CO2 ] within the Soybean Free Air Concentration Enrichment facility (SoyFACE) in central Illinois. This treatment resulted in a statistically significant 8% yield increase. This is the first direct proof that a modern crop cultivar produces more leaf than is optimal for yield under today's and future [CO2 ] and that reducing leaf area would give higher yields. Breeding or bioengineering for lower leaf area could, therefore, contribute very significantly to meeting future demand for staple food crops given that an 8% yield increase across the USA alone would amount to 6.5 million metric tons annually.

Effect of intracoronary nicardipine on cardiac enzymes after elective percutaneous coronary intervention.

BACKGROUND: Elevation in cardiac enzymes after percutaneous coronary intervention (PCI) is common and is associated with adverse clinical outcomes. HYPOTHESIS: Administration of intracoronary nicardipine--a calcium channel blocker will reduce cardiac enzyme levels in patients undergoing elective PCI. METHODS: In a single center, prospective, double-blind placebo-controlled trial, 193 patients undergoing elective PCI (with or without stenting) for chronic stable angina and/or an abnormal stress test were randomized to receive 200 mcg of intracoronary nicardipine (n = 93) or saline solution (n = 100) prior to intervention. Cardiac enzyme levels were measured immediately and at 8 and 16 hours after the procedure. Major adverse clinical events (MACE) were assessed at 30 days and at 6 months. RESULTS: Incidence of periprocedural myonecrosis defined as elevation of troponin I levels > 1x the upper limit of normal was similar in both groups (placebo 15.4% vs drug 10.6%; P = 0.47). There was no significant difference in peak troponin I levels after PCI between the 2 groups (placebo 0.58 ng/mL +/- 1.08 ng/mL vs drug 0.97 ng/mL +/- 3.6 ng/mL; P = 0.35). Major adverse clinical events at 6 months were infrequent and not statistically different in the 2 groups (placebo 3.4% vs drug 1.2%; P = 0.52). Multivariate analysis revealed that pretreatment with nicardipine was not associated with reduction in the incidence of troponin I elevation (odds ratio [OR]: 0.54; 95% confidence interval [CI]: 0.18-1.6; P = 0.28). CONCLUSIONS: In low-risk patients undergoing elective PCI, intracoronary nicardipine administration did not produce a significant cardioprotective effect in reducing postprocedural cardiac enzymes leakage.

Delayed manifestation of a mid-esophageal tear with profuse hemorrhage after transesophageal echocardiogram.

Esophageal injury or perforation is a rare but life threatening complication of transesophageal echocardiogram (TEE). Most of the patients manifest symptoms within 24 hours of the procedure and upper esophagus is the most common site of injury. We report a patient who underwent TEE for the evaluation of severe valvular insufficiency and 4 days after the procedure developed an esophageal tear in its mid portion associated with profuse upper gastrointestinal bleeding. Though delayed esophageal perforation in the lower segment has been previously reported after a perioperative TEE, no such report exists to our knowledge, in the setting of a nonsurgical TEE.

Cardiovascular surgical outcomes in patients with the antiphospholipid syndrome--a case-series.

BACKGROUND: Patients with the antiphospholipid syndrome (APLS) have severe involvement of the cardiovascular apparatus and often need surgical interventions to correct these manifestations. Few studies that have looked at the outcomes of cardiothoracic surgeries in APLS patients have reported high rates of perioperative mortality and thromboembolic events. OBJECTIVE: Our goal was to examine the outcomes of adult APLS patients undergoing coronary artery bypass surgery (CABG) and/or valvular surgery. We also wanted to determine whether aggressive anticoagulation therapy could prevent life threatening thromboembolic complications in these patients. METHODS: We retrospectively reviewed medical records of nine patients with primary APLS undergoing cardiothoracic surgery between 1985 and 2005 at our institution. Patient demographics, operative procedures and one-year clinical outcomes were obtained. RESULTS: Forty-five percent of our patients had more than three cardiovascular risk factors other than APLS. There were no mortalities in our case series. However, 89% of our patients developed major complications. Despite aggressive anticoagulation, 37.5% developed thromboembolic events including cerebrovascular accidents, myocardial infarctions and vena caval thrombosis. Other complications included heparin-induced thrombocytopenia, redo of CABG surgery and sepsis. CONCLUSION: Despite aggressive anticoagulation and lack of significant pre-operative co-morbidities, APLS patients undergoing cardiothoracic surgery appear to have high rates of post-operative clinical events.

Transient left ventricular apical ballooning after cocaine use: is catecholamine cardiotoxicity the pathologic link?

We describe a patient who developed acute chest pain after using cocaine and had ST-segment elevation in the anterior leads on electrocardiography with mild elevation of cardiac enzymes. Cardiac catheterization showed normal coronary arteries with no coronary vasospasm. Left ventricular angiography revealed typical ballooning of the left ventricular apex during systole with an estimated left ventricular ejection fraction of 25%. The symptoms improved during the next few hours, and follow-up echocardiography 4 days later showed complete resolution of the left ventricular dysfunction. Transient left ventricular apical ballooning (LVAB) was diagnosed. To our knowledge, LVAB (also known as Takotsubo cardiomyopathy or "broken heart syndrome") has not been reported previously in association with cocaine use. We discuss the possible pathophysiologic link between LVAB and cocaine-induced cardiotoxicity.

The no-reflow phenomenon: epidemiology, pathophysiology, and therapeutic approach.

Over the past 20 years, advances in the management of ST segment elevation myocardial infarction have focused on the rapid achievement of patency in the infarct-related artery. The limitation of this therapeutic strategy has been exposed with the development of diagnostic techniques to assess coronary microcirculation, including myocardial contrast echo, magnetic resonance imaging, myocardial perfusion grading, and the coronary flow wire. These methods have expanded our ability to understand and recognize the no-reflow phenomenon, which describes the absence of tissue perfusion despite epicardial coronary artery patency and flow. Although the mechanisms responsible for the development of no reflow are not fully understood, the end result is microvascular damage produced by microvascular obstruction or reperfusion injury. Ideally, early recognition of the no-reflow phenomenon should provide an opportunity for therapeutic intervention designed to augment tissue perfusion and maintain the viability of myocardium at risk. A number of pharmacologic agents are being used in conjunction with percutaneous transluminal coronary angioplasty in an attempt to improve microvascular perfusion. These include IIb/IIIa receptor antagonists, adenosine, verapamil, and the experimental agent nicorandil. In the new millennium, the emphasis of reperfusion therapy is being shifted downstream from its exclusive focus on the epicardial artery to assuring normal blood flow at the tissue level. This article will review the epidemiology, pathophysiology, and therapeutic approach to this vexing clinical problem.

Reducing radiocontrast use in the cardiac catheterization laboratory--a behavioral modification approach.

OBJECTIVES: This study assessed the impact of behavioral modification techniques on reducing the volume of contrast dye used during cardiac catheterization and percutaneous coronary intervention (PCI). BACKGROUND: Excessive administration of radiocontrast agents in the catheterization laboratory is associated with numerous adverse effects including radiocontrast nephropathy. This may be precipitated by using large volumes of contrast dye, particularly in diabetic patients and those with pre-existing renal dysfunction. METHODS: Data were prospectively collected on 20,322 consecutive patients undergoing cardiac catheterization and PCI between January 1997 and December 2001. A focused behavioral modification program was initiated in late 1998. The physician was informed verbally during the course of the procedure and by letter after the procedure regarding the volume of contrast dye used for cases in which the radiocontrast volume exceeded 300 mL. Data were analyzed using the Fischer's exact test. RESULTS: In the prefeedback years (1997 and 1998), high contrast use occurred in 7.7% (n = 602) of the total cases (n = 7799). In the postfeedback years (1999, 2000, and 2001), this declined to 3.6% (n = 445) of the total cases (n = 12,523), representing a 53% reduction (P < .001). The effect was most pronounced in PCI, with the percentage of high contrast cases decreasing from 24% (n = 563) of the total PCI cases (n = 2348) to 10.6% (n = 359) of the total PCI cases (n = 3386), representing a 56% reduction (P < .001). CONCLUSIONS: Our study demonstrates the effectiveness of behavioral modification and the contribution it can make in reducing the volume of contrast dye used in the cardiac catheterization laboratory, particularly in PCI. Adoption of such strategies may enhance patient safety and reduce contribution it can make in reducing the volume of contrast dye used in the cardiac catheterization laboratory, particularly in PCI. Adoption of such strategies may enhance patient safety and reduce costs.

Successful intervention for high-output cardiac failure caused by massive renal arteriovenous fistula-a case report.

Renal arteriovenous fistula is a rare clinical entity that may produce high-output cardiac failure. This report describes the case of an 81-year-old woman in whom recurrent episodes of congestive heart failure developed over a relatively short time. A massive renal arteriovenous fistula was visualized by CT scan and arteriography. Successful embolization was performed under hemodynamic monitoring with complete resolution of the patient's symptoms.