Stomatal, mesophyll and biochemical limitations to photosynthesis and their relationship with leaf structure over an elevation gradient in two conifers.

Photosynthetic responses across complex elevational gradients provides insight into fundamental processes driving responses of plant growth and net primary production to environmental change. Gas exchange of needles and twig water potential were measured in two widespread coniferous tree species, Pinus contorta and Picea engelmannii, over an 800-m elevation gradient in southeastern Wyoming, USA. We hypothesized that limitations to photosynthesis imposed by mesophyll conductance (gm) would be greatest at the highest elevation sites due to higher leaf mass per area (LMA) and that estimations of maximum rate of carboxylation (Vcmax) without including gm would obscure elevational patterns of photosynthetic capacity. We found that gm decreased with elevation for P. contorta and remained constant for P. engelmannii, but in general, limitation to photosynthesis by gm was small. Indeed, estimations of Vcmax when including gm were equivalent to those estimated without including gm and no correlation was found between gm and LMA nor between gm and leaf N. Stomatal conductance (gs) and biochemical demand for CO2 were by far the most limiting processes to photosynthesis at all sites along the elevation gradient. Photosynthetic capacity (A) and gs were influenced strongly by differences in soil water availability across the elevation transect, while gm was less responsive to water availability. Based on our analysis, variation in gm plays only a minor role in driving patterns of photosynthesis in P. contorta and P. engelmannii across complex elevational gradients in dry, continental environments of the Rocky Mountains and accurate modeling of photosynthesis, growth and net primary production in these forests may not require detailed estimation of this trait value.

Global change impacts on cacti (Cactaceae): current threats, challenges and conservation solutions.

BACKGROUND: The plant family Cactaceae provides some of the most striking examples of adaptive evolution, expressing undeniably the most spectacular New World radiation of succulent plants distributed across arid and semi-arid regions of the Americas. Cacti are widely regarded for their cultural, economic and ecological value, yet they are also recognized as one of the most threatened and endangered taxonomic groups on the planet. SCOPE: This paper reviews current threats to species of cacti that have distributions in arid to semi-arid subtropical regions. Our review focuses primarily on four global change forces: (1) increases in atmospheric CO2 concentrations; (2) increases in mean annual temperatures and heat waves; (3) increases in the duration, frequency and intensity of droughts; and (4) and increases in competition and wildfire frequency from invasion by non-native species. We provide a broad range of potential priorities and solutions for stemming the extinction risk of cacti species and populations. CONCLUSIONS: Mitigating ongoing and emerging threats to cacti will require not only strong policy initiatives and international cooperation, but also new and creative approaches to conservation. These approaches include determining species at risk from climate extremes, enhancing habitat quality after disturbance, approaches and opportunities for ex situ conservation and restoration, and the potential use of forensic tools for identifying plants that have been removed illegally from the wild and sold on open markets.

Micronutrient deficiencies in critically ill patients receiving continuous renal replacement therapy.

BACKGROUND & AIMS: Continuous renal replacement therapy (CRRT) is essential to the management of acute kidney injury (AKI) in critical illness. Unfortunately, large quantities of micronutrients are shown to be lost in CRRT effluent. Current literature describes serum micronutrient values in CRRT patients to be below-reference range, yet seldom compares such values to other critically ill populations unexposed to CRRT. The aim of this study was to describe and compare the prevalence of micronutrient and carnitine deficiencies in critically ill patients at high malnutrition risk exposed to CRRT to a group of patient unexposed to CRRT. METHODS: A retrospective chart review was conducted at Duke University Hospital using the electronic medical record. The study group consisted of patients at high malnutrition risk requiring intensive care unit (ICU) admission from 01/01/2017-12/31/2018 with one or more of the following serum micronutrient levels checked: carnitine, copper, zinc, selenium, and vitamins B1, B6, B9, and C. Micronutrient deficiencies were defined as below the reference range and carnitine deficiencies were interpreted as an acyl to free carnitine ratio (ACFR) of >0.4. RESULTS: 106 ICU patients met inclusion criteria and 46% were exposed to CRRT. At least one micronutrient deficiency was reported in 90% of CRRT patients compared to 61% patients unexposed to CRRT (p = 0.002). A greater percentage of copper (p < 0.001) and carnitine (p < 0.001) deficiencies were found among patients exposed to CRRT, while more zinc deficiencies were noted among non-CRRT patients (p = 0.001). CONCLUSIONS: The vast majority of CRRT patients presented with micronutrient deficiencies. Clinicians should have a heightened awareness of the risk for serum copper, carnitine, and vitamin B6 deficiencies among CRRT patients. Further prospective and randomized-controlled trials are needed to better define this new category of malnutrition and test supplementation strategies to address and prevent these clinically-relevant deficiencies.

Trading water for carbon in the future: Effects of elevated CO2 and warming on leaf hydraulic traits in a semiarid grassland.

The effects of climate change on plants and ecosystems are mediated by plant hydraulic traits, including interspecific and intraspecific variability of trait phenotypes. Yet, integrative and realistic studies of hydraulic traits and climate change are rare. In a semiarid grassland, we assessed the response of several plant hydraulic traits to elevated CO2 (+200 ppm) and warming (+1.5 to 3°C; day to night). For leaves of five dominant species (three graminoids and two forbs), and in replicated plots exposed to 7 years of elevated CO2 , warming, or ambient climate, we measured: stomatal density and size, xylem vessel size, turgor loss point, and water potential (pre-dawn). Interspecific differences in hydraulic traits were larger than intraspecific shifts induced by elevated CO2 and/or warming. Effects of elevated CO2 were greater than effects of warming, and interactions between treatments were weak or not detected. The forbs showed little phenotypic plasticity. The graminoids had leaf water potentials and turgor loss points that were 10% to 50% less negative under elevated CO2 ; thus, climate change might cause these species to adjust their drought resistance strategy away from tolerance and toward avoidance. The C4 grass also reduced allocation of leaf area to stomata under elevated CO2 , which helps explain observations of higher soil moisture. The shifts in hydraulic traits under elevated CO2 were not, however, simply due to higher soil moisture. Integration of our results with others' indicates that common species in this grassland are more likely to adjust stomatal aperture in response to near-term climate change, rather than anatomical traits; this contrasts with apparent effects of changing CO2 on plant anatomy over evolutionary time. Future studies should assess how plant responses to drought may be constrained by the apparent shift from tolerance (via low turgor loss point) to avoidance (via stomatal regulation and/or access to deeper soil moisture).

Association between early postoperative nutritional supplement utilisation and length of stay in malnourished hip fracture patients.

BACKGROUND: Malnutrition in older hip fracture patients is associated with increased complication rates and mortality. As postoperative nutrition delivery is essential to surgical recovery, postoperative nutritional supplements including oral nutritional supplements or tube feeding formulas can improve postoperative outcomes in malnourished hip/femur fracture patients. The association between early postoperative nutritional supplements utilisation and hospital length of stay was assessed in malnourished hip/femur fracture patients. METHODS: This is a retrospective cohort study of malnourished hip/femur fracture patients undergoing surgery from 2008 to 2018. Patients were identified through International Classification of Diseases, Ninth Revision (ICD-9) and Tenth Revision (ICD-10) codes and nutritional supplement utilisation via hospital charge codes. The primary outcome was hospital length of stay. Secondary outcomes included infectious complications, hospital mortality, ICU admission, and costs. Propensity matching (1:1) and univariable analysis were performed. RESULTS: Overall, 160 151 hip/femur fracture surgeries were identified with a coded-malnutrition prevalence of 8.7%. Early postoperative nutritional supplementation (by hospital day 1) occurred in 1.9% of all patients and only 4.9% of malnourished patients. Propensity score matching demonstrated early nutritional supplements were associated with significantly shorter length of stay (5.8 [6.6] days vs 7.6 [5.8] days; P<0.001) without increasing hospital costs. No association was observed between early nutritional supplementation and secondary outcomes. CONCLUSION: Malnutrition is underdiagnosed in hip/femur fracture patients, and nutritional supplementation is underutilised. Early nutritional supplementation was associated with a significantly shorter hospital stay without an increase in costs. Nutritional supplementation in malnourished hip/femur fracture patients could serve as a key target for perioperative quality improvement.

Postoperative Utilization of Oral Nutrition Supplements in Surgical Patients in US Hospitals.

BACKGROUND: Postoperative nutrition delivery is essential to surgical recovery; unfortunately, postoperative dietary intake is often poor. Recent surgical guidelines recommend use of oral nutritional supplements (ONS) to improve nutrition delivery. Our aim was to examine prevalence of coded ONS use over time and coded malnutrition rates in postoperative patients. METHODS: The Premier Healthcare Database (PHD) was queried for postoperative patients found to have charges for ONS between 2008-2014. ONS use identified via charge codes. Descriptive statistics utilized to examine prevalence of malnutrition and ONS utilization. Multilevel, multivariable logistic regression models were fit to examine factors associated with ONS use. RESULTS: A total of 2,823,532 surgical encounters were identified in PHD in 172 hospitals utilizing ONS charge codes. ONS-receiving patients were 72% Caucasian, 65% Medicare patients with mean age of 66 ± 16.5 years. Compared with patients not receiving ONS, ONS patients had higher van Walraven severity scores (7.3 ± 7.8 vs 2.3 ± 5.6, P < .001) with greater comorbidities. Overall coded malnutrition prevalence was 4.3%. Coded malnutrition diagnosis increased from 4.4% to 5.2% during study period. Only 15% of malnourished patients received ONS. Individual hospital practice explained much of variation in early postoperative ONS use. CONCLUSION: In this large surgical population, inpatient ONS use is most common in older, Caucasian, Medicare patients with high comorbidity burden. Despite increased malnutrition during study period, observed ONS prescription rate did not increase. Our data indicate current ONS utilization in surgical patients, even coded with malnutrition, is limited and is a critical perioperative quality improvement opportunity.

Impact of early postoperative oral nutritional supplement utilization on clinical outcomes in colorectal surgery.

BACKGROUND: Small randomized trials of early postoperative oral nutritional supplementation (ONS) suggest various health benefits following colorectal surgery (CRS). However, real-world evidence of the impact of early ONS on clinical outcomes in CRS is lacking. METHODS: Using a nationwide administrative-financial database (Premier Healthcare Database), we examined the association between early ONS use and postoperative clinical outcomes in patients undergoing elective open or laparoscopic CRS between 2008 and 2014. Early ONS was defined as the presence of charges for ONS before postoperative day (POD) 3. The primary outcome was composite infectious complications. Key secondary efficacy (intensive care unit (ICU) admission and gastrointestinal complications) and falsification (blood transfusion and myocardial infarction) outcomes were also examined. Propensity score matching was used to assemble patient groups that were comparable at baseline, and differences in outcomes were examined. RESULTS: Overall, patients receiving early ONS were older with greater comorbidities and more likely to be Medicare beneficiaries with malnutrition. In a well-matched sample of early ONS recipients (n = 267) versus non-recipients (n = 534), infectious complications were significantly lower in early ONS recipients (6.7% vs. 11.8%, P < 0.03). Early ONS use was also associated with significantly reduced rates of pneumonia (P < 0.04), ICU admissions (P < 0.04), and gastrointestinal complications (P < 0.05). There were no significant differences in falsification outcomes. CONCLUSIONS: Although early postoperative ONS after CRS was more likely to be utilized in elderly patients with greater comorbidities, the use of early ONS was associated with reduced infectious complications, pneumonia, ICU admission, and gastrointestinal complications. This propensity score-matched study using real-world data suggests that clinical outcomes are improved with early ONS use, a simple and inexpensive intervention in CRS patients.

Climate warming alters photosynthetic responses to elevated CO2 in prairie plants.

PREMISE: The impact of elevated CO2 concentration ([CO2 ]) and climate warming on plant productivity in dryland ecosystems is influenced strongly by soil moisture availability. We predicted that the influence of warming on the stimulation of photosynthesis by elevated [CO2 ] in prairie plants would operate primarily through direct and indirect effects on soil water. METHODS: We measured light-saturated photosynthesis (Anet ), stomatal conductance (gs ), maximum Rubisco carboxylation rate (Vcmax ), maximum electron transport capacity (Jmax ) and related variables in four C3 plant species in the Prairie Heating and CO2 Enrichment (PHACE) experiment in southeastern Wyoming. Measurements were conducted over two growing seasons that differed in the amount of precipitation and soil moisture content. RESULTS: Anet in the C3 subshrub Artemisia frigida and the C3 forb Sphaeralcea coccinea was stimulated by elevated [CO2 ] under ambient and warmed temperature treatments. Warming by itself reduced Anet in all species during the dry year, but stimulated photosynthesis in S. coccinea in the wet year. In contrast, Anet in the C3 grass Pascopyrum smithii was not stimulated by elevated [CO2 ] or warming under wet or dry conditions. Photosynthetic downregulation under elevated [CO2 ] in this species countered the potential stimulatory effect under improved water relations. Warming also reduced the magnitude of CO2 -induced down-regulation in this grass, possibly by sustaining high levels of carbon utilization. CONCLUSIONS: Direct and indirect effects of elevated [CO2 ] and warming on soil water was an overriding factor influencing patterns of Anet in this semi-arid temperate grassland, emphasizing the important role of water relations in driving grassland responses to global change.

Geospatial Variations and Neighborhood Deprivation in Drug-Related Admissions and Overdoses.

Drug overdoses are a national and global epidemic. However, while overdoses are inextricably linked to social, demographic, and geographical determinants, geospatial patterns of drug-related admissions and overdoses at the neighborhood level remain poorly studied. The objective of this paper is to investigate spatial distributions of patients admitted for drug-related admissions and overdoses from a large, urban, tertiary care center using electronic health record data. Additionally, these spatial distributions were adjusted for a validated socioeconomic index called the Area Deprivation Index (ADI). We showed spatial heterogeneity in patients admitted for opioid, amphetamine, and psychostimulant-related diagnoses and overdoses. While ADI was associated with drug-related admissions, it did not correct for spatial variations and could not account alone for this spatial heterogeneity.

Hydraulic and photosynthetic limitations prevail over root non-structural carbohydrate reserves as drivers of resprouting in two Mediterranean oaks.

Resprouting is an ancestral trait in angiosperms that confers resilience after perturbations. As climate change increases stress, resprouting vigor is declining in many forest regions, but the underlying mechanism is poorly understood. Resprouting in woody plants is thought to be primarily limited by the availability of non-structural carbohydrate reserves (NSC), but hydraulic limitations could also be important. We conducted a multifactorial experiment with two levels of light (ambient, 2-3% of ambient) and three levels of water stress (0, 50 and 80 percent losses of hydraulic conductivity, PLC) on two Mediterranean oaks (Quercus ilex and Q. faginea) under a rain-out shelter (n = 360). The proportion of resprouting individuals after canopy clipping declined markedly as PLC increased for both species. NSC concentrations affected the response of Q. ilex, the species with higher leaf construction costs, and its effect depended on the PLC. The growth of resprouting individuals was largely dependent on photosynthetic rates for both species, while stored NSC availability and hydraulic limitations played minor and non-significant roles, respectively. Contrary to conventional wisdom, our results indicate that resprouting in oaks may be primarily driven by complex interactions between hydraulics and carbon sources, whereas stored NSC play a significant but secondary role.

Tutorial: Development and Implementation of a Multidisciplinary Preoperative Nutrition Optimization Clinic.

Although much is known about surgical risk, little evidence exists regarding how best to proactively address preoperative risk factors to improve surgical outcomes. Preoperative malnutrition is a widely prevalent and modifiable risk factor in patients undergoing surgery. Malnutrition prior to surgery portends significantly higher postoperative mortality, morbidity, length of stay, readmission rates, and hospital costs. Unfortunately, perioperative malnutrition is poorly screened for and remains largely unrecognized and undertreated-a true "silent epidemic" in surgical care. To better address this silent epidemic of surgical nutrition risk, here we describe the rationalization, development, and implementation of a multidisciplinary, registered dietitian-driven, preoperative nutrition optimization clinic program designed to improve perioperative outcomes and reduce cost. Implementation of this novel Perioperative Enhancement Team (POET) Nutrition Clinic required a collaboration among many disciplines, as well as an identified need for multidimensional scheduling template development, data tracking systems, dashboard development, and integration of electronic health records. A structured malnutrition risk score (Perioperative Nutrition Screen score) was developed and is being validated. A structured malnutrition pathway was developed and is under study. Finally, the POET Nutrition Clinic has established a novel role for a perioperative registered dietitian as the integral point person to deliver perioperative nutrition care. We hope this structured model of perioperative nutrition assessment and optimization will allow for wide implementation and generalizability in other centers worldwide to improve recognition and treatment of perioperative nutrition risk.

Perioperative Nutrition Care of Orthopedic Surgery Patient.

Despite evidence that malnutrition is associated with significant complications in orthopedic surgery1, unrecognized malnutrition continues to be a "silent epidemic", effecting up to 50% of hospitalized patients. Specifically, pre-surgical malnutrition is associated with increased risk for surgical site infections, increased length of hospital stay, and increased health care costs in patients following total joint arthroplasty. Serologic markers (i.e. serum albumin and total lymphocyte count), anthropometric measurements, (i.e. calf muscle circumference and triceps skin fold) and assessment and screening tools (i.e. The Rainey-MacDonald Nutritional Index, the Mini Nutrition Assessment Short Form, the Malnutrition Universal Screening Tool and the Nutrition Risk Screening 2002) have all been used to aid in the diagnosis of malnutrition in orthopedic patients, yet there is no universal gold standard for screening or assessing nutritional risk and no accepted guideline for perioperative nutritional optimization in this patient population. Recently, the Perioperative Nutrition Screen (PONS) was introduced2 as an easy and efficient way to preoperatively identify and risk stratify patients for malnutrition in order to guide perioperative nutrition optimization. Given malnutrition is associated with increased risk of surgical site infections and increased length of hospital stay, adequate assessment of perioperative risk for malnutrition and preoperative nutrition optimization, including structured weight loss in the obese population, consumption of high protein oral nutritional supplements, immunonutrition oral supplements and adequate glucose control, may improve perioperative outcomes. The presence of a Registered Dietician (RD) should be a standard of care in all pre-operative clinics to improve nutrition care and surgical outcomes.

Focused cardiac ultrasound in preoperative assessment: the perioperative provider's new stethoscope?

Focused cardiac ultrasound (FoCUS)-a simplified, qualitative version of echocardiography-is a well-established tool in the armamentarium of critical care and emergency medicine. This review explores the extent to which FoCUS could also be used to enhance the preoperative physical examination to better utilise resources and identify those who would benefit most from detailed echocardiography prior to surgery. Among the range of pathologies that FoCUS can screen for, the conditions it provides the most utility in the preoperative setting are left ventricular systolic dysfunction (LVSD) and, in certain circumstances, significant aortic stenosis (AS). Thus, FoCUS could help answer two common preoperative diagnostic questions. First, in a patient with high cardiovascular risk who subjectively reports a good functional status, is there evidence of LVSD? Second, does an asymptomatic patient with a systolic murmur have significant aortic stenosis? Importantly, many cardiac pathologies of relevance to perioperative care fall outside the scope of FoCUS, including regional wall motion abnormalities, diastolic dysfunction, left ventricular outflow obstruction, and pulmonary hypertension. Current evidence suggests that after structured training in FoCUS and performance of 20-30 supervised examinations, clinicians can achieve competence in basic cardiac ultrasound image acquisition. However, it is not known precisely how many training exams are necessary to achieve competence in FoCUS image interpretation. Given the short history of FoCUS use in preoperative evaluation, further research is needed to determine what additional questions FoCUS is suited to answer in the pre-operative setting.

Trypanosoma brucei Secreted Aromatic Ketoacids Activate the Nrf2/HO-1 Pathway and Suppress Pro-inflammatory Responses in Primary Murine Glia and Macrophages.

African trypanosomes, such as Trypanosoma brucei (T. brucei), are protozoan parasites of the mammalian vasculature and central nervous system that are best known for causing fatal human sleeping sickness. As exclusively extracellular parasites, trypanosomes are subject to constant challenge from host immune defenses but they have developed very effective strategies to evade and modulate these responses to maintain an infection while simultaneously prolonging host survival. Here we investigate host parasite interactions, especially within the CNS context, which are not well-understood. We demonstrate that T. brucei strongly upregulates the stress response protein, Heme Oxygenase 1 (HO-1), in primary murine glia and macrophages in vitro. Furthermore, using a novel AHADHinT. brucei cell line, we demonstrate that specific aromatic ketoacids secreted by bloodstream forms of T. brucei are potent drivers of HO-1 expression and are capable of inhibiting pro-IL1ß induction in both glia and macrophages. Additionally, we found that these ketoacids significantly reduced IL-6 and TNFα production by glia, but not macrophages. Finally, we present data to support Nrf2 activation as the mechanism of action by which these ketoacids upregulate HO-1 expression and mediate their anti-inflammatory activity. This study therefore reports a novel immune evasion mechanism, whereby T. brucei secretes amino-acid derived metabolites for the purpose of suppressing both the host CNS and peripheral immune response, potentially via induction of the Nrf2/HO-1 pathway.

Pharmacological interventions for chronic pain in children: an overview of systematic reviews.

We know little about the safety or efficacy of pharmacological medicines for children and adolescents with chronic pain, despite their common use. Our aim was to conduct an overview review of systematic reviews of pharmacological interventions that purport to reduce pain in children with chronic noncancer pain (CNCP) or chronic cancer-related pain (CCRP). We searched the Cochrane Database of Systematic Reviews, Medline, EMBASE, and DARE for systematic reviews from inception to March 2018. We conducted reference and citation searches of included reviews. We included children (0-18 years of age) with CNCP or CCRP. We extracted the review characteristics and primary outcomes of ≥30% participant-reported pain relief and patient global impression of change. We sifted 704 abstracts and included 23 systematic reviews investigating children with CNCP or CCRP. Seven of those 23 reviews included 6 trials that involved children with CNCP. There were no randomised controlled trials in reviews relating to reducing pain in CCRP. We were unable to combine data in a meta-analysis. Overall, the quality of evidence was very low, and we have very little confidence in the effect estimates. The state of evidence of randomized controlled trials in this field is poor; we have no evidence from randomised controlled trials for pharmacological interventions in children with cancer-related pain, yet cannot deny individual children access to potential pain relief. Prospero ID: CRD42018086900.

Giant cacti: isotopic recorders of climate variation in warm deserts of the Americas.

The plant family Cactaceae is considered among the most threatened groups of organisms on the planet. The threatened status of the cacti family has created a renewed interest in the highly evolved physiological and morphological traits that underpin their persistence in some of the harshest subtropical environments in the Americas. Among the most important anatomical features of cacti is the modification of leaves into spines, and previous work has shown that the stable isotope chemistry of cacti spines records potential variations in stem water balance, stress, and Crassulacean acid metabolism (CAM). We review the opportunities, challenges, and pitfalls in measuring δ 13C, δ 2H, and δ 18O ratios captured in spine tissues that potentially reflect temporal and spatial patterns of stomatal conductance, internal to atmospheric CO2 partial pressures, and subsequent patterns of photosynthetic gas exchange. We then evaluate the challenges in stable isotope analysis in spine tissues related to variation in CAM expression, stem water compartmentalization, and spine whole-tissue composition among other factors. Finally, we describe how the analysis of all three isotopes can be used in combination to provide potentially robust analysis of photosynthetic function in cacti, and other succulent-stemmed taxa across broad spatio-temporal environmental gradients.

Nitrogen deposition sources and patterns in the Greater Yellowstone Ecosystem determined from ion exchange resin collectors, lichens, and isotopes.

Over the past century, atmospheric nitrogen deposition (Ndep) has increased across the western United States due to agricultural and urban development, resulting in degraded ecosystem quality. Regional patterns of Ndep are often estimated by coupling direct measurements from large-scale monitoring networks and atmospheric chemistry models, but such efforts can be problematic in the western US because of complex terrain and sparse sampling. This study aimed not only to understand Ndep patterns in mountainous ecosystems but also to investigate whether isotope values of lichens and throughfall deposition can be used to determine Ndep sources, and serve as an additional tool in ecosystem health assessments. We measured Ndep amounts and δ15N in montane conifer forests of the Greater Yellowstone Ecosystem using canopy throughfall and bulk monitors and lichens. In addition, we examined patterns of C:N ratios in lichens as a possible indicator of lichen physiological condition. The isotopic signature of δ15N of Ndep helps to discern emission sources, because δ15N of NOx from combustion tends to be high (-5 to +25‰) while NHx from agricultural sources tends to be comparatively low (-40 to -10‰). Summertime Ndep increased with elevation and ranged from 0.26 to 1.66 kg ha-1. Ndep was higher than expected in remote areas. The δ15N values of lichens were typically -15.3 to -10‰ suggesting agriculture as a primary emission source of deposition. Lichen %N, δ15N and C:N ratios can provide important information about Ndep sources and patterns over small spatial scales in complex terrain.