Growth regulation by apyrases: Insights from altering their expression level in different organisms.

Apyrase (APY) enzymes are nucleoside triphosphate (NTP) diphosphohydrolases that can remove the terminal phosphate from NTPs and nucleoside diphosphates but not from nucleoside monophosphates. They have conserved structures and functions in yeast, plants, and animals. Among the most studied APYs in plants are those in Arabidopsis (Arabidopsis thaliana; AtAPYs) and pea (Pisum sativum; PsAPYs), both of which have been shown to play major roles in regulating plant growth and development. Valuable insights on their functional roles have been gained by transgenically altering their transcript abundance, either by constitutively expressing or suppressing APY genes. This review focuses on recent studies that have provided insights on the mechanisms by which APY activity promotes growth in different organisms. Most of these studies have used transgenic lines that constitutively expressed APY in multiple different plants and in yeast. As APY enzymatic activity can also be changed post-translationally by chemical blockage, this review also briefly covers studies that used inhibitors to suppress APY activity in plants and fungi. It concludes by summarizing some of the main unanswered questions about how APYs regulate plant growth and proposes approaches to answering them.

Polarized distribution of extracellular nucleotides promotes gravity-directed polarization of development in spores of Ceratopteris richardii.

Gravity directs the polarization of Ceratopteris fern spores. This process begins with the uptake of calcium through channels at the bottom of the spore, a step necessary for the gravity response. Data showing that extracellular ATP (eATP) regulates calcium channels led to the hypothesis that extracellular nucleotides could play a role in the gravity-directed polarization of Ceratopteris spores. In animal and plant cells ATP can be released from mechanosensitive channels. This report tests the hypothesis that the polarized release of ATP from spores could be activated by gravity, preferentially along the bottom of the spore, leading to an asymmetrical accumulation of eATP. In order to carry out this test, an ATP biosensor was used to measure the [eATP] at the bottom and top of germinating spores during gravity-directed polarization. The [eATP] along the bottom of the spore averaged 7-fold higher than the concentration at the top. All treatments that disrupted eATP signaling resulted in a statistically significant decrease in the gravity response. In order to investigate the source of ATP release, spores were treated with Brefeldin A (BFA) and gadolinium trichloride (GdCl3). These treatments resulted in a significant decrease in gravity-directed polarization. An ATP biosensor was also used to measure ATP release after treatment with both BFA and GdCl3. Both of these treatments caused a significant decrease in [ATP] measured around spores. These results support the hypothesis that ATP could be released from mechanosensitive channels and secretory vesicles during the gravity-directed polarization of Ceratopteris spores.

Two distinct light-induced reactions are needed to promote germination in spores of Ceratopteris richardii.

Germination of Ceratopteris richardii spores is initiated by light and terminates 3-4 days later with the emergence of a rhizoid. Early studies documented that the photoreceptor for initiating this response is phytochrome. However, completion of germination requires additional light input. If no further light stimulus is given after phytochrome photoactivation, the spores do not germinate. Here we show that a crucial second light reaction is required, and its function is to activate and sustain photosynthesis. Even in the presence of light, blocking photosynthesis with DCMU after phytochrome photoactivation blocks germination. In addition, RT-PCR showed that transcripts for different phytochromes are expressed in spores in darkness, and the photoactivation of these phytochromes results in the increased transcription of messages encoding chlorophyll a/b binding proteins. The lack of chlorophyll-binding protein transcripts in unirradiated spores and their slow accumulation makes it unlikely that photosynthesis is required for the initial light reaction. This conclusion is supported by the observation that the transient presence of DCMU, only during the initial light reaction, had no effect on germination. Additionally, the [ATP] in Ceratopteris richardii spores increased coincidentally with the length of light treatment during germination. Overall, these results support the conclusion that two distinct light reactions are required for the germination of Ceratopteris richardii spores.

Prognostic association between d-dimer thresholds and 30-day pulmonary embolism diagnosis among emergency department patients with suspected SARS-CoV-2 infection: a Canadian COVID-19 Emergency Department Rapid Response Network study.

OBJECTIVE: The primary objective was to quantify the prognostic association between various D-dimer thresholds and 30-day PE diagnosis among emergency department (ED) patients with suspected SARS-CoV-2 infection. METHODS: This was a retrospective study of patients enrolled in the Canadian COVID-19 ED Rapid Response Network (CCEDRRN) registry from March 1, 2020 to July 2, 2021. We included consecutive adults (≥ 18 years) presenting to 49 EDs with chest pain, shortness of breath, hypoxia, syncope, presyncope, or hemoptysis who were tested for both SARS-CoV-2 and D-dimer at index ED visit. The primary outcome measure was the sensitivity, specificity, and negative predictive value of D-dimer test thresholds for the outcome of 30-day PE diagnosis. RESULTS: Among 10,837 patients included in our study, 404 (3.7%) were diagnosed with PE at 30-days. A standard D-Dimer threshold of 500 ng/mL had a sensitivity of 97.8% (95% confidence interval [CI] 95.8-99.0%), specificity of 40.9% (95% CI 39.9-41.8%), and negative predictive value of 99.8% (95% CI 99.6-99.9%). An age-adjusted D-dimer threshold had a sensitivity of 96.0% (95% CI 93.6-97.7%), specificity of 48.5% (95% CI 47.5-49.4%), and negative predictive value of 99.7% (95% CI 99.5-99.8%). D-dimer testing had slightly lower prognostic performance among SARS-CoV-2 positive compared to SARS-CoV-2 negative patients in predicting 30-day PE diagnosis. CONCLUSIONS: Among ED patients with suspected SARS-CoV-2, the standard 500 ng/mL and age-adjusted D-dimer thresholds were comparable for the prediction of PE at 30-days. The prognostic performance of D-dimer was lower among SARS-CoV-2 positive patients. TRIAL REGISTRATION: Clinicaltrials.gov, NCT04702945.

RéSUMé: OBJECTIF: L'objectif principal était de quantifier l'association pronostique entre différents seuils de D-dimères et le diagnostic d'EP à 30 jours chez les patients des services d'urgence suspectés d'être infectés par le SRAS-CoV-2. MéTHODES: Il s'agissait d'une étude rétrospective des patients inscrits au registre du réseau canadien de réponse rapide aux urgences COVID-19 (CCEDRRN) du 1er mars 2020 au 2 juillet 2021. Nous avons inclus des adultes consécutifs (>18 ans) se présentant dans 49 services d'urgence pour une douleur thoracique, un essoufflement, une hypoxie, une syncope, une présyncope ou une hémoptysie et qui ont été testés à la fois pour le SRAS-CoV-2 et les D-dimères lors de la visite de référence aux urgences. Le principal critère d'évaluation était la sensibilité, la spécificité et la valeur prédictive négative des seuils du test des D-dimères pour le diagnostic de l'EP à 30 jours. RéSULTATS: Parmi les 10 837 patients inclus dans notre étude, 404 (3,7 %) ont reçu un diagnostic d'EP à 30 jours. Un seuil standard de D-Dimer de 500 ng/mL avait une sensibilité de 97,8 % (intervalle de confiance [IC] à 95 % 95,8-99,0 %), une spécificité de 40,9 % (IC à 95 % 39,9-41,8 %) et une valeur prédictive négative de 99,8 % (IC à 95 % 99,6-99,9 %). Un seuil de D-dimères ajusté à l'âge avait une sensibilité de 96,0% (IC à 95 % 93,6-97,7 %), une spécificité de 48,5% (IC à 95 % 47,5-49,4 %) et une valeur prédictive négative de 99,7 % (IC à 95 % 99,5-99,8 %). Le test des D-dimères avait une performance pronostique légèrement inférieure chez les patients positifs pour le SRAS-CoV-2 par rapport aux patients négatifs pour le SRAS-CoV-2 en ce qui concerne la prédiction du diagnostic d'EP à 30 jours. CONCLUSIONS: Chez les patients des urgences suspectés d'être atteints du SRAS-CoV-2, les seuils standard de 500 ng/ml et les seuils de D-dimères ajustés à l'âge étaient comparables pour la prédiction de l'EP à 30 jours. La performance pronostique des D-dimères était plus faible chez les patients positifs pour le SRAS-CoV-2. ENREGISTREMENT DE L'ESSAI: Clinicaltrials.gov, NCT04702945.

A History of the Concept of Interpersonal Relations in Nursing Based on the Psychiatric Nursing Textbook Literature.

Many nurses would assume that interpersonal relations in nursing is a reasonably modern concept that originated with work of Hildagarde Peplau in 1952. However, there is evidence of concepts and ideas that resonate with interpersonal relations being evident in the psychiatric nursing textbook literature from its beginnings in 1885. The aim of this article is to provide an outline of ideas about interpersonal relations in nursing as presented in the psychiatric nursing textbook literature between 1885 and 2013 and trace the development of these ideas over that timeframe.This study uses Bevir's methodology known as The Logic of the History of Ideas. This is a post-analytical framework. Concepts related to interpersonal relation in nursing can be found throughout the psychiatric nursing textbook literature. The language may not be consistent with current language use but nevertheless, the ideas and concepts evident in the literature do demonstrate a consistent presence of thinking about interpersonal relations.

Constitutive expression of a pea apyrase, psNTP9, increases seed yield in field-grown soybean.

To address the demand for food by a rapidly growing human population, agricultural scientists have carried out both plant breeding and genetic engineering research. Previously, we reported that the constitutive expression of a pea apyrase (Nucleoside triphosphate, diphosphohydrolase) gene, psNTP9, under the control of the CaMV35S promoter, resulted in soybean plants with an expanded root system architecture, enhanced drought resistance and increased seed yield when they are grown in greenhouses under controlled conditions. Here, we report that psNTP9-expressing soybean lines also show significantly enhanced seed yields when grown in multiple different field conditions at multiple field sites, including when the gene is introgressed into elite germplasm. The transgenic lines have higher leaf chlorophyll and soluble protein contents and decreased stomatal density and cuticle permeability, traits that increase water use efficiency and likely contribute to the increased seed yields of field-grown plants. These altered properties are explained, in part, by genome-wide gene expression changes induced by the transgene.

APYRASE1/2 mediate red light-induced de-etiolation growth in Arabidopsis seedlings.

In etiolated seedlings, red light (R) activates phytochrome and initiates signals that generate major changes at molecular and physiological levels. These changes include inhibition of hypocotyl growth and promotion of the growth of primary roots, apical hooks, and cotyledons. An earlier report showed that the sharp decrease in hypocotyl growth rapidly induced by R was accompanied by an equally rapid decrease in the transcript and protein levels of two closely related apyrases (APYs; nucleoside triphosphate-diphosphohydrolases) in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, enzymes whose expression alters auxin transport and growth in seedlings. Here, we report that single knockouts of either APY inhibit R-induced promotion of the growth of primary roots, apical hooks, and cotyledons, and RNAi-induced suppression of APY1 expression in the background of apy2 inhibits R-induced apical hook opening. When R-irradiated primary roots and apical hook-cotyledons began to show a gradual increase in their growth relative to dark controls, they concurrently showed increased levels of APY protein, but in hook-cotyledon tissue, this occurred without parallel increases in their transcripts. In wild-type seedlings whose root growth is suppressed by the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the R-induced increased APY expression in roots was also inhibited. In unirradiated plants, the constitutive expression of APY2 promoted both hook opening and changes in the transcript abundance of Small Auxin Upregulated RNA (SAUR), SAUR17 and SAUR50 that help mediate de-etiolation. These results provide evidence that the expression of APY1/APY2 is regulated by R and that APY1/APY2 participate in the signaling pathway by which phytochrome induces differential growth changes in different tissues of etiolated seedlings.

qSOFA does not predict bacteremia in patients with severe manifestations of sepsis.

BACKGROUND: Bloodstream infections in septic patients may be missed due to preceding antibiotic therapy prior to obtaining blood cultures. We leveraged the FABLED cohort study to determine if the quick Sequential Organ Failure Assessment (qSOFA) score could reliably identify patients at higher risk of bacteremia in patients who may have false negative blood cultures due to previously administered antibiotic therapy. METHODS: We conducted a multi-centre diagnostic study among adult patients with severe manifestations of sepsis. Patients were enrolled in one of seven participating centres between November 2013 and September 2018. All patients from the FABLED cohort had two sets of blood cultures drawn prior to the administration of antimicrobial therapy, as well as additional blood cultures within 4 hours of treatment initiation. Participants were categorized according to qSOFA score, with a score ≥2 being considered positive. RESULTS: Among 325 patients with severe manifestations of sepsis, a positive qSOFA score (defined as a score ≥2) on admission was 58% sensitive (95% CI 48% to 67%) and 41% specific (95% CI 34% to 48%) for predicting bacteremia. Among patients with negative post-antimicrobial blood cultures, a positive qSOFA score was 57% sensitive (95% CI 42% to 70%) and 42% specific (95% CI 35% to 49%) to detect patients who were originally bacteremic prior to the initiation of therapy. CONCLUSIONS: Our results suggest that the qSOFA score cannot be used to identify patients at risk for occult bacteremia due to the administration of antibiotics pre-blood culture.

HISTORIQUE: Les infections sanguines peuvent rester non diagnostiquées chez les patients septiques avant l'obtention des cultures sanguines, en raison d'une antibiothérapie antérieure. Les chercheurs ont puisé dans l'étude de cohorte FABLED pour déterminer si le score rapide de l'évaluation séquentielle d'insuffisance des organes (Sequential Organ Failure Assessment, qSOFA) pourrait dépister les patients à plus haut risque de bactériémie avec fiabilité, malgré la possibilité de cultures sanguines faussement négatives en raison d'une antibiothérapie antérieure. MÉTHODOLOGIE: Les chercheurs ont réalisé une étude diagnostique multicentrique chez des patients adultes ayant de graves manifestations de sepsis. Les patients ont été inscrits dans l'un des sept centres participants entre novembre 2013 et septembre 2018. Tous les patients de l'étude de cohorte FABLED avaient subi deux séries de cultures sanguines avant de recevoir une thérapie antimicrobienne, de même qu'une autre série de cultures sanguines dans les quatre heures suivant le début du traitement. Les participants ont été classés en fonction de leur score de qSOFA, un score d'au moins 2 étant considéré comme positif. RÉSULTATS: Chez les 325 patients ayant de graves manifestations de sepsis, un score de qSOFA positif (défini comme un score d'au moins 2) à l'admission était sensible à 58 % (IC à 95 %, 48 % à 67 %) et spécifique à 41 % (IC à 95 %, 34 % à 48 %) pour prédire la bactériémie. Chez les patients dont les cultures sanguines étaient négatives après la prise d'antimicrobiens, un score de qSOFA positif était sensible à 57 % (IC à 95 %, 42 % à 70 %) et spécifique à 42 % (IC à 95 %, 35 % à 49 %) pour dépister les patients atteints d'une bactériémie avant le début du traitement. CONCLUSIONS: Selon les résultats, le score de qSOFA ne peut pas être utilisé pour dépister les patients à risque de bactériémie occulte à cause de l'administration d'antibiotiques avant la culture sanguine.

RAFF-3 Trial: A Stepped-Wedge Cluster Randomised Trial to Improve Care of Acute Atrial Fibrillation and Flutter in the Emergency Department.

BACKGROUND: We sought to improve care of patients with acute atrial fibrillation (AF) and flutter (AFL) in the emergency department (ED) by implementing the Canadian Association of Emergency Physicians (CAEP) Acute AF/AFL Best Practices Checklist. METHODS: We conducted a stepped-wedge cluster randomised trial at 11 large community and academic hospital EDs in 5 Canadian provinces and enrolled consecutive AF/AFL patients. The study intervention was introduction of the CAEP Checklist with the use of a knowledge translation-implementation approach that included behaviour change techniques and organisation/system-level strategies. The primary outcome was length of stay in ED, and secondary outcomes were discharge home, use of rhythm control, adverse events, and 30-day status. Analysis used mixed-effects regression adjusting for covariates. RESULTS: Patient visits in the control (n = 314) and intervention (n = 404) periods were similar with mean age 62.9 years, 54% male, 71% onset < 12 hours, and 86% AF, 14% AFL. We observed a reduction in length of stay of 20.9% (95% confidence interval [CI] 5.5%-33.8%; P = 0.01), an increase in use of rhythm control (adjusted odds ratio [OR] 4.5, 95% CI 1.8-11.6; P = 0.002), and a decrease in use of rate-control medications (OR 0.5, 95% CI 0.2-0.9; P = 0.02). There was no change in adverse events and no strokes or deaths by 30 days. CONCLUSIONS: The RAFF-3 trial led to optimised care of AF/AFL patients with decreased ED lengths of stay, increased ED rhythm control by drug or electricity, and no increase in adverse events. Early cardioversion allows AF/AFL patients to quickly resume normal activities.

Neither Blood Culture Positivity nor Time to Positivity Is Associated With Mortality Among Patients Presenting With Severe Manifestations of Sepsis: The FABLED Cohort Study.

BACKGROUND: Sepsis is a leading cause of morbidity, mortality, and health care costs worldwide. METHODS: We conducted a multicenter, prospective cohort study evaluating the yield of blood cultures drawn before and after empiric antimicrobial administration among adults presenting to the emergency department with severe manifestations of sepsis. Enrolled patients who had the requisite blood cultures drawn were followed for 90 days. We explored the independent association between blood culture positivity and its time to positivity in relation to 90-day mortality. RESULTS: Three hundred twenty-five participants were enrolled; 90-day mortality among the 315 subjects followed up was 25.4% (80/315). Mortality was associated with age (mean age [standard deviation] in those who died was 72.5 [15.8] compared with 62.9 [17.7] years among survivors; P < .0001), greater Charlson Comorbidity Index (2 [interquartile range {IQR}, 1-3] vs 1 [IQR, 0-3]; P = .008), dementia (13/80 [16.2%] vs 18/235 [7.7%]; P = .03), cancer (27/80 [33.8%] vs 47/235 [20.0%]; P = .015), positive quick Sequential Organ Failure Assessment score (57/80 [71.2%] vs 129/235 [54.9%]; P = .009), and normal white blood cell count (25/80 [31.2%] vs 42/235 [17.9%]; P = .02). The presence of bacteremia, persistent bacteremia after antimicrobial infusion, and shorter time to blood culture positivity were not associated with mortality. Neither the source of infection nor pathogen affected mortality. CONCLUSIONS: Although severe sepsis is an inflammatory condition triggered by infection, its 90-day survival is not influenced by blood culture positivity nor its time to positivity. CLINICAL TRIALS REGISTRATION: NCT01867905.

Recent Advances Clarifying the Structure and Function of Plant Apyrases (Nucleoside Triphosphate Diphosphohydrolases).

Studies implicating an important role for apyrase (NTPDase) enzymes in plant growth and development began appearing in the literature more than three decades ago. After early studies primarily in potato, Arabidopsis and legumes, especially important discoveries that advanced an understanding of the biochemistry, structure and function of these enzymes have been published in the last half-dozen years, revealing that they carry out key functions in diverse other plants. These recent discoveries about plant apyrases include, among others, novel findings on its crystal structures, its biochemistry, its roles in plant stress responses and its induction of major changes in gene expression when its expression is suppressed or enhanced. This review will describe and discuss these recent advances and the major questions about plant apyrases that remain unanswered.

Trauma Care During the COVID-19 Pandemic: A Canadian Survey.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has placed major limitations on trauma health care systems. This survey aims to identify how Canadian trauma centres altered their processes to care for injured patients and protect their staff during the pandemic. METHODS: A survey was distributed to trauma directors at level 1 Canadian adult trauma centres in July 2020. Questions included changes made to the trauma service in preparation for the pandemic, modification to clinical practice and expected lasting modifications after the pandemic. RESULTS: The response rate was 68.4%. All trauma centres modified their treatment and investigation protocols for the pandemic. Most respondents adopted online platforms for meetings and educational activities and used simulation to prepare for COVID-19-infected trauma patients. The approach to who would intubate trauma patients, which trauma patients should be tested for COVID-19 and who should use N95 ventilators, varied among the sites surveyed. CONCLUSION: All centres modified some of their treatment and investigation protocols for the pandemic but not all modifications were adopted universally. Knowing these steps and comparing them with other global centres will help organize disaster plans for the current and future pandemics.

Real-world Time to Positivity of 2 Widely Used Commercial Blood Culture Systems in Patients With Severe Manifestations of Sepsis: An Analysis of the FABLED Study.

BACKGROUND: Of all microbiological tests performed, blood cultures have the most impact on patient care. Timely results are essential, especially in the management of sepsis. While there are multiple available blood culture systems on the market, they have never been compared in a prospective study in a critically ill population. METHODS: We performed an analysis of the FABLED study cohort to compare culture results and time to positivity (TTP) of 2 widely used blood culture systems: BacT/Alert and BACTEC. In this multisite prospective study, patients with severe manifestations of sepsis had cultures drawn before antibiotics using systematic enrollment criteria and blood drawing methodology allowing for minimization of pre-analytical biases. RESULTS: We enrolled 315 patients; 144 had blood cultures (47 positive) with BacT/Alert and 171 with BACTEC (53 positive). Patients whose blood cultures were processed using the BacT/Alert system were younger (median, 64 vs 70 years; P = .003), had a higher proportion of HIV (9.03% vs 1.75%; P = .008) and a lower qSOFA (P = .003). There were no statistically significant differences in the most commonly identified bacterial species. TTP was shorter for BACTEC (median [interquartile range {IQR}], 12.5 [10-14] hours) compared with BacT/Alert (median [IQR], 17 [14-21] hours; P < .0001). CONCLUSIONS: In this large prospective multi-centre study comparing the two blood culture systems among patients with severe manifestations of sepsis, and using a rigorous pre-analytical methodology, the BACTEC system yielded positive culture results 4.5 hours earlier than BacT/Alert. These results apply to commonly isolated bacteria. However, our study design did not allow direct comparison of TTP for unusual pathogens nor of clinical sensitivity between systems. More research is needed to determine the clinical implications of this finding.

Interactive youth science workshops benefit student participants and graduate student mentors.

Science communication and outreach are essential for training the next generation of scientists and raising public awareness for science. Providing effective science, technology, engineering, and mathematics (STEM) educational outreach to students in classrooms is challenging because of the need to form partnerships with teachers, the time commitment required for the presenting scientist, and the limited class time allotted for presentations. In our Present Your Ph.D. Thesis to a 12-Year Old outreach project, our novel solution to this problem is hosting a youth science workshop (YSW) on our university campus. The YSW is an interpersonal science communication and outreach experience in which graduate students from diverse scientific disciplines introduce middle and high school students to their cutting-edge research and mentor them to develop a white-board presentation to communicate the research to the workshop audience. Our assessment of the YSW indicated that participating young students expressed significantly more positive attitudes toward science and increased motivation to work in a STEM career after attending the workshop. Qualitative follow-up interviews with participating graduate students' show that even with minimal time commitment, an impactful science communication training experience can be achieved. The YSW is a low-cost, high-reward educational outreach event amenable to all disciplines of science. It enhances interest and support of basic science research while providing opportunities for graduate students to engage with the public, improve their science communication skills, and enhance public understanding of science. This YSW model can be easily implemented at other higher education institutions to globally enhance science outreach initiatives.

Blood Culture Results Before and After Antimicrobial Administration in Patients With Severe Manifestations of Sepsis: A Diagnostic Study.

Background: Administering antimicrobial agents before obtaining blood cultures could potentially decrease time to treatment and improve outcomes, but it is unclear how this strategy affects diagnostic sensitivity. Objective: To determine the sensitivity of blood cultures obtained shortly after initiation of antimicrobial therapy in patients with severe manifestations of sepsis. Design: Patient-level, single-group, diagnostic study. (ClinicalTrials.gov: NCT01867905). Setting: 7 emergency departments in North America. Participants: Adults with severe manifestations of sepsis, including systolic blood pressure less than 90 mm Hg or a serum lactate level of 4 mmol/L or more. Intervention: Blood cultures were obtained before and within 120 minutes after initiation of antimicrobial treatment. Measurements: Sensitivity of blood cultures obtained after initiation of antimicrobial therapy. Results: Of 3164 participants screened, 325 were included in the study (mean age, 65.6 years; 62.8% men) and had repeated blood cultures drawn after initiation of antimicrobial therapy (median time, 70 minutes [interquartile range, 50 to 110 minutes]). Preantimicrobial blood cultures were positive for 1 or more microbial pathogens in 102 of 325 (31.4%) patients. Postantimicrobial blood cultures were positive for 1 or more microbial pathogens in 63 of 325 (19.4%) patients. The absolute difference in the proportion of positive blood cultures between pre- and postantimicrobial testing was 12.0% (95% CI, 5.4% to 18.6%; P < 0.001). Sensitivity of postantimicrobial culture was 52.9% (CI, 42.8% to 62.9%). When the results of other microbiological cultures were included, microbial pathogens were found in 69 of 102 (67.6% [CI, 57.7% to 76.6%]) patients. Limitation: Only a proportion of screened patients were recruited. Conclusion: Among patients with severe manifestations of sepsis, initiation of empirical antimicrobial therapy significantly reduces the sensitivity of blood cultures drawn shortly after treatment initiation. Primary Funding Source: Vancouver Coastal Health, St. Paul's Hospital Foundation Emergency Department Support Fund, the Fonds de recherche Santé-Québec, and the Maricopa Medical Foundation.

Ectopic expression of a pea apyrase enhances root system architecture and drought survival in Arabidopsis and soybean.

Ectoapyrases (ecto-NTPDases) function to decrease levels of extracellular ATP and ADP in animals and plants. Prior studies showed that ectopic expression of a pea ectoapyrase, psNTP9, enhanced growth in Arabidopsis seedlings and that the overexpression of the two Arabidopsis apyrases most closely related to psNTP9 enhanced auxin transport and growth in Arabidopsis. These results predicted that ectopic expression of psNTP9 could promote a more extensive root system architecture (RSA) in Arabidopsis. We confirmed that transgenic Arabidopsis seedlings had longer primary roots, more lateral roots, and more and longer root hairs than wild-type plants. Because RSA influences water uptake, we tested whether the transgenic plants could tolerate osmotic stress and water deprivation better than wild-type plants, and we confirmed these properties. Transcriptomic analyses revealed gene expression changes in the transgenic plants that helped account for their enhanced RSA and improved drought tolerance. The effects of psNTP9 were not restricted to Arabidopsis, because its expression in soybeans improved the RSA, growth, and seed yield of this crop and supported higher survival in response to drought. Our results indicate that in both Arabidopsis and soybeans, the constitutive expression of psNTP9 results in a more extensive RSA and improved survival in drought stress conditions.

Role of Ca2+ in Mediating Plant Responses to Extracellular ATP and ADP.

Among the most recently discovered chemical regulators of plant growth and development are extracellular nucleotides, especially extracellular ATP (eATP) and extracellular ADP (eADP). Plant cells release ATP into their extracellular matrix under a variety of different circumstances, and this eATP can then function as an agonist that binds to a specific receptor and induces signaling changes, the earliest of which is an increase in the concentration of cytosolic calcium ([Ca2+]cyt). This initial change is then amplified into downstream-signaling changes that include increased levels of reactive oxygen species and nitric oxide, which ultimately lead to major changes in the growth rate, defense responses, and leaf stomatal apertures of plants. This review presents and discusses the evidence that links receptor activation to increased [Ca2+]cyt and, ultimately, to growth and diverse adaptive changes in plant development. It also discusses the evidence that increased [Ca2+]cyt also enhances the activity of apyrase (nucleoside triphosphate diphosphohydrolase) enzymes that function in multiple subcellular locales to hydrolyze ATP and ADP, and thus limit or terminate the effects of these potent regulators.

ANN1 and ANN2 Function in Post-Phloem Sugar Transport in Root Tips to Affect Primary Root Growth.

Annexins are a multigene family of calcium-dependent membrane-binding proteins that play important roles in plant cell signaling. Annexins are multifunctional proteins, and their function in plants is not comprehensively understood. Arabidopsis (Arabidopsis thaliana) annexins ANN1 and ANN2 are 64% identical in their primary structure, and both are highly expressed in seedlings. Here, we showed that ann-mutant seedlings grown in the absence of sugar show decreased primary root growth and altered columella cells in root caps; however, these mutant defects are rescued by Suc, Glc, or Fru. In seedlings grown without sugar, significant up-regulation of photosynthetic gene expression and chlorophyll accumulation was found in ann-mutant cotyledons compared to that in wild type, which indicates potential sugar starvation in the roots of ann-mutant seedlings. Unexpectedly, the overall sugar content of ann-mutant primary roots was significantly higher than that of wild-type roots when grown without sugar. To examine the diffusion of sugar along the entire root to the root tip, we examined the unloading pattern of carboxyfluorescein dye and found that post-phloem sugar transport was impaired in ann-mutant root tips compared to that in wild type. Increased levels of ROS and callose were detected in the root tips of ann-mutant seedlings grown without Suc, the latter of which would restrict plasmodesmal sugar transport to root tips. Our results indicate that ANN1 and ANN2 play an important role in post-phloem sugar transport to the root tip, which in turn indirectly influences photosynthetic rates in cotyledons. This study expands our understanding of the function of annexins in plants.

Effects of Discovery, Iteration, and Collaboration in Laboratory Courses on Undergraduates' Research Career Intentions Fully Mediated by Student Ownership.

Course-based undergraduate research experiences (CUREs) provide a promising avenue to attract a larger and more diverse group of students into research careers. CUREs are thought to be distinctive in offering students opportunities to make discoveries, collaborate, engage in iterative work, and develop a sense of ownership of their lab course work. Yet how these elements affect students' intentions to pursue research-related careers remain unexplored. To address this knowledge gap, we collected data on three design features thought to be distinctive of CUREs (discovery, iteration, collaboration) and on students' levels of ownership and career intentions from ∼800 undergraduates who had completed CURE or inquiry courses, including courses from the Freshman Research Initiative (FRI), which has a demonstrated positive effect on student retention in college and in science, technology, engineering, and mathematics. We used structural equation modeling to test relationships among the design features and student ownership and career intentions. We found that discovery, iteration, and collaboration had small but significant effects on students' intentions; these effects were fully mediated by student ownership. Students in FRI courses reported significantly higher levels of discovery, iteration, and ownership than students in other CUREs. FRI research courses alone had a significant effect on students' career intentions.

Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells.

Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.