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Phosphomimetic T335D Mutation of Hydroxypyruvate Reductase 1 Modifies Cofactor Specificity and Impacts Arabidopsis Growth in Air

Photorespiration is an essential process in oxygenic photosynthetic organisms triggered by the oxygenase activity of Rubisco. In peroxisomes, photorespiratory HYDROXYPYRUVATE REDUCTASE1 (HPR1) catalyzes the conversion of hydroxypyruvate to glycerate together with the oxidation of a pyridine nucleotide cofactor. HPR1 regulation remains poorly understood; however, HPR1 phosphorylation at T335 has been reported. By comparing the kinetic properties of phosphomimetic (T335D), nonphosphorylatable (T335A), and wild-type recombinant Arabidopsis (Arabidopsis thaliana) HPR1, it was found that HPR1-T335D exhibits reduced NADH-dependent hydroxypyruvate reductase activity while showing improved NADPH-dependent activity. Complementation of the Arabidopsis hpr1-1 mutant by either wild-type HPR1 or HPR1-T335A fully complemented the photorespiratory growth phenotype of hpr1-1 in ambient air, whereas HPR1-T335D-containing hpr1-1 plants remained smaller and had lower photosynthetic CO2 assimilation rates. Metabolite analyses indicated that these phenotypes were associated with subtle perturbations in the photorespiratory cycle of HPR1-T335D-complemented hpr1-1 rosettes compared to all other HPR1-containing lines. Therefore, T335 phosphorylation may play a role in the regulation of HPR1 activity in planta, although it was not required for growth under ambient air controlled conditions. Furthermore, improved NADP-dependent HPR1 activities in peroxisomes could not compensate for the reduced NADH-dependent HPR1 activity.




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ONE-HELIX PROTEIN1 and 2 Form Heterodimers to Bind Chlorophyll in Photosystem II Biogenesis

Members of the light-harvesting complex protein family participate in multiple processes connected with light sensing, light absorption, and pigment binding within the thylakoid membrane. Amino acid residues of the light-harvesting chlorophyll a/b-binding proteins involved in pigment binding have been precisely identified through x-ray crystallography experiments. In vitro pigment-binding studies have been performed with LIGHT-HARVESTING-LIKE3 proteins, and the pigment-binding ability of cyanobacterial high-light-inducible proteins has been studied in detail. However, analysis of pigment binding by plant high-light-inducible protein homologs, called ONE-HELIX PROTEINS (OHPs), is lacking. Here, we report on successful in vitro reconstitution of Arabidopsis (Arabidopsis thaliana) OHPs with chlorophylls and carotenoids and show that pigment binding depends on the formation of OHP1/OHP2 heterodimers. Pigment-binding capacity was completely lost in each of the OHPs when residues of the light-harvesting complex chlorophyll-binding motif required for chlorophyll binding were mutated. Moreover, the mutated OHP variants failed to rescue the respective knockout (T-DNA insertion) mutants, indicating that pigment-binding ability is essential for OHP function in vivo. The scaffold protein HIGH CHLOROPHYLL FLUORESCENCE244 (HCF244) is tethered to the thylakoid membrane by the OHP heterodimer. We show that HCF244 stability depends on OHP heterodimer formation and introduce the concept of a functional unit consisting of OHP1, OHP2, and HCF244, in which each protein requires the others. Because of their pigment-binding capacity, we suggest that OHPs function in the delivery of pigments to the D1 subunit of PSII.




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The Occurrence of Sulfated Salicinoids in Poplar and Their Formation by Sulfotransferase1

Salicinoids form a specific class of phenolic glycosides characteristic of the Salicaceae. Although salicinoids accumulate in large amounts and have been shown to be involved in plant defense, their biosynthesis is unclear. We identified two sulfated salicinoids, salicin-7-sulfate and salirepin-7-sulfate, in black cottonwood (Populus trichocarpa). Both compounds accumulated in high amounts in above-ground tissues including leaves, petioles, and stems, but were also found at lower concentrations in roots. A survey of salicin-7-sulfate and salirepin-7-sulfate in a subset of poplar (Populus sp.) and willow (Salix sp.) species revealed a broader distribution within the Salicaceae. To elucidate the formation of these compounds, we studied the sulfotransferase (SOT) gene family in P. trichocarpa (PtSOT). One of the identified genes, PtSOT1, was shown to encode an enzyme able to convert salicin and salirepin into salicin-7-sulfate and salirepin-7-sulfate, respectively. The expression of PtSOT1 in different organs of P. trichocarpa matched the accumulation of sulfated salicinoids in planta. Moreover, RNA interference-mediated knockdown of SOT1 in gray poplar (Populus x canescens) resulted in decreased levels of sulfated salicinoids in comparison to wild-type plants, indicating that SOT1 is responsible for their formation in planta. The presence of a nonfunctional SOT1 allele in black poplar (Populus nigra) was shown to correlate with the absence of salicin-7-sulfate and salirepin-7-sulfate in this species. Food choice experiments with leaves from wild-type and SOT1 knockdown trees suggest that sulfated salicinoids do not affect the feeding preference of the generalist caterpillar Lymantria dispar. A potential role of the sulfated salicinoids in sulfur storage and homeostasis is discussed.




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Compensatory Guaiacyl Lignin Biosynthesis at the Expense of Syringyl Lignin in 4CL1-Knockout Poplar

The lignin biosynthetic pathway is highly conserved in angiosperms, yet pathway manipulations give rise to a variety of taxon-specific outcomes. Knockout of lignin-associated 4-coumarate:CoA ligases (4CLs) in herbaceous species mainly reduces guaiacyl (G) lignin and enhances cell wall saccharification. Here we show that CRISPR-knockout of 4CL1 in poplar (Populus tremula x alba) preferentially reduced syringyl (S) lignin, with negligible effects on biomass recalcitrance. Concordant with reduced S-lignin was downregulation of ferulate 5-hydroxylases (F5Hs). Lignification was largely sustained by 4CL5, a low-affinity paralog of 4CL1 typically with only minor xylem expression or activity. Levels of caffeate, the preferred substrate of 4CL5, increased in line with significant upregulation of caffeoyl shikimate esterase1. Upregulation of caffeoyl-CoA O-methyltransferase1 and downregulation of F5Hs are consistent with preferential funneling of 4CL5 products toward G-lignin biosynthesis at the expense of S-lignin. Thus, transcriptional and metabolic adaptations to 4CL1-knockout appear to have enabled 4CL5 catalysis at a level sufficient to sustain lignification. Finally, genes involved in sulfur assimilation, the glutathione-ascorbate cycle, and various antioxidant systems were upregulated in the mutants, suggesting cascading responses to perturbed thioesterification in lignin biosynthesis.




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Dehydroascorbate Reductases and Glutathione Set a Threshold for High-Light-Induced Ascorbate Accumulation

Plants require a high concentration of ascorbate as a redox buffer for survival under stress conditions, such as high light. Dehydroascorbate reductases (DHARs) are enzymes that catalyze the reduction of DHA to ascorbate using reduced glutathione (GSH) as an electron donor, allowing rapid ascorbate recycling. However, a recent study using an Arabidopsis (Arabidopsis thaliana) triple mutant lacking all three DHAR genes (herein called dhar) did not find evidence for their role in ascorbate recycling under oxidative stress. To further study the function of DHARs, we generated dhar Arabidopsis plants as well as a quadruple mutant line combining dhar with an additional vtc2 mutation that causes ascorbate deficiency. Measurements of ascorbate in these mutants under low- or high-light conditions indicated that DHARs have a nonnegligible impact on full ascorbate accumulation under high light, but that they are dispensable when ascorbate concentrations are low to moderate. Because GSH itself can reduce DHA nonenzymatically, we used the pad2 mutant that contains ~30% of the wild-type GSH level. The pad2 mutant accumulated ascorbate at a wild-type level under high light; however, when the pad2 mutation was combined with dhar, there was near-complete inhibition of high-light–dependent ascorbate accumulation. The lack of ascorbate accumulation was consistent with a marked increase in the ascorbate degradation product threonate. These findings indicate that ascorbate recycling capacity is limited in dhar pad2 plants, and that both DHAR activity and GSH content set a threshold for high-light–induced ascorbate accumulation.




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Transcription Factors BLH2 and BLH4 Regulate Demethylesterification of Homogalacturonan in Seed Mucilage

The polysaccharide pectin is a major component of the plant cell wall. The pectic glycan homogalacturonan (HG) is a proportionally small but important component of a specialized seed cell wall called mucilage. HG is synthesized in a highly methylesterified form, and, following secretion, is de-methylesterified by pectin methylesterases (PMEs). The degree of methylesterification of HG determines the structural and functional properties of pectin, but how methylesterification is regulated remains largely unknown. Here, we identified two BEL1-Like homeodomain (BLH) transcription factors, BLH2 and BLH4, as positive regulators of HG de-methylesterification in Arabidopsis (Arabidopsis thaliana) seed coat mucilage. BLH2 and BLH4 were significantly expressed in mucilage secretory cells during seed mucilage production. BLH2 and BLH4 single mutants exhibited no obvious mucilage phenotype, but the blh2 blh4 double mutant displayed significantly reduced mucilage adherence to the seed. Reduced mucilage adherence in blh2 blh4 was caused by decreased PME activity in the seed coat, which increased the degree of methylesterification of HG in mucilage. The expression of several PME metabolism-related genes, including PME58, PECTIN METHYLESTERASE INHIBITOR6, SEEDSTICK, and MYB52 was significantly altered in blh2 blh4 seeds. BLH2 and BLH4 directly activated PME58 expression by binding to its TGACAGGT cis-element. Moreover, pme58 mutants exhibited reduced mucilage adherence similar to that of blh2 blh4, and the blh2 blh4 pme58 triple mutant exhibited no additional mucilage adherence defects. Furthermore, overexpression of PME58 in blh2 blh4 rescued the mucilage adherence defect. Together, these results demonstrate that BLH2 and BLH4 redundantly regulate de-methylesterification of HG in seed mucilage by directly activating PME58.




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Allelic Mutations in the Ripening-Inhibitor Locus Generate Extensive Variation in Tomato Ripening

RIPENING INHIBITOR (RIN) is a transcription factor with transcriptional activator activity that plays a major role in regulating fruit ripening in tomato (Solanum lycopersicum). Recent studies have revealed that (1) RIN is indispensable for full ripening but not for the induction of ripening; and (2) the rin mutation, which produces nonripening fruits that never turn red or soften, is not a null mutation but instead converts the encoded transcriptional activator into a repressor. Here, we have uncovered aspects of RIN function by characterizing a series of allelic mutations within this locus that were produced by CRISPR/Cas9. Fruits of RIN-knockout plants, which are characterized by partial ripening and low levels of lycopene but never turn fully red, showed excess flesh softening compared to the wild type. The knockout mutant fruits also showed accelerated cell wall degradation, suggesting that, contrary to the conventional view, RIN represses over-ripening in addition to facilitating ripening. A C-terminal domain-truncated RIN protein, encoded by another allele of the RIN locus (rinG2), did not activate transcription but formed transcription factor complexes that bound to target genomic regions in a manner similar to that observed for wild-type RIN protein. Fruits expressing this truncated RIN protein exhibited extended shelf life, but unlike rin fruits, they accumulated lycopene and appeared orange. The diverse ripening properties of the RIN allelic mutants suggest that substantial phenotypic variation can be produced by tuning the activity of a transcription factor.




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Specific Lhc Proteins Are Bound to PSI or PSII Supercomplexes in the Diatom Thalassiosira pseudonana

Despite the ecological relevance of diatoms, many aspects of their photosynthetic machinery remain poorly understood. Diatoms differ from the green lineage of oxygenic organisms by their photosynthetic pigments and light-harvesting complex (Lhc) proteins, the latter of which are also called fucoxanthin-chlorophyll proteins (FCP). These are composed of three groups of proteins: Lhcf as the main group, Lhcr that are PSI associated, and Lhcx that are involved in photoprotection. The FCP complexes are assembled in trimers and higher oligomers. Several studies have investigated the biochemical properties of purified FCP complexes, but limited knowledge is available about their interaction with the photosystem cores. In this study, isolation of stable supercomplexes from the centric diatom Thalassiosira pseudonana was achieved. To preserve in vivo structure, the separation of thylakoid complexes was performed by native PAGE and sucrose density centrifugation. Different subpopulations of PSI and PSII supercomplexes were isolated and their subunits identified. Analysis of Lhc antenna composition identified Lhc(s) specific for either PSI (Lhcr 1, 3, 4, 7, 10–14, and Lhcf10) or PSII (Lhcf 1–7, 11, and Lhcr2). Lhcx6_1 was reproducibly found in PSII supercomplexes, whereas its association with PSI was unclear. No evidence was found for the interaction between photosystems and higher oligomeric FCPs, comprising Lhcf8 as the main component. Although the subunit composition of the PSII supercomplexes in comparison with that of the trimeric FCP complexes indicated a close mutual association, the higher oligomeric pool is only weakly associated with the photosystems, albeit its abundance in the thylakoid membrane.




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Sensory-Directed Genetic and Biochemical Characterization of Volatile Terpene Production in Kiwifruit

Terpene volatiles are found in many important fruit crops, but their relationship to flavor is poorly understood. Here, we demonstrate using sensory descriptive and discriminant analysis that 1,8-cineole contributes a key floral/eucalyptus note to the aroma of ripe 'Hort16A’ kiwifruit (Actinidia chinensis). Two quantitative trait loci (QTLs) for 1,8-cineole production were identified on linkage groups 27 and 29a in a segregating A. chinensis population, with the QTL on LG29a colocating with a complex cluster of putative terpene synthase (TPS)-encoding genes. Transient expression in Nicotiana benthamiana and analysis of recombinant proteins expressed in Escherichia coli showed four genes in the cluster (AcTPS1a–AcTPS1d) encoded functional TPS enzymes, which produced predominantly sabinene, 1,8-cineole, geraniol, and springene, respectively. The terpene profile produced by AcTPS1b closely resembled the terpenes detected in red-fleshed A. chinensis. AcTPS1b expression correlated with 1,8-cineole content in developing/ripening fruit and also showed a positive correlation with 1,8-cineole content in the mapping population, indicating the basis for segregation is an expression QTL. Transient overexpression of AcTPS1b in Actinidia eriantha fruit confirmed this gene produced 1,8-cineole in Actinidia. Structure-function analysis showed AcTPS1a and AcTPS1b are natural variants at key TPS catalytic site residues previously shown to change enzyme specificity in vitro. Together, our results indicate that AcTPS1b is a key gene for production of the signature flavor terpene 1,8-cineole in ripe kiwifruit. Using a sensory-directed strategy for compound identification provides a rational approach for applying marker-aided selection to improving flavor in kiwifruit as well as other fruits.




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SUMOylation Stabilizes the Transcription Factor DREB2A to Improve Plant Thermotolerance

Heat stress (HS) has serious effects on plant development, resulting in heavy agricultural losses. A critical transcription factor network is involved in plant adaptation to high temperature. DEHYDRATION RESPONSIVE ELEMENT-BINDING PROTEIN2A (DREB2A) is a key transcription factor that functions in plant thermotolerance. The DREB2A protein is unstable under normal temperature and is degraded by the 26S proteasome; however, the mechanism by which DREB2A protein stability dramatically increases in response to HS remains poorly understood. In this study, we found that the DREB2A protein of Arabidopsis (Arabidopsis thaliana) is stabilized under high temperature by the posttranslational modification SUMOylation. Biochemical data indicated that DREB2A is SUMOylated at K163, a conserved residue adjacent to the negative regulatory domain during HS. SUMOylation of DREB2A suppresses its interaction with BPM2, a ubiquitin ligase component, consequently increasing DREB2A protein stability under high temperature. In addition, analysis of plant heat tolerance and marker gene expression indicated that DREB2A SUMOylation is essential for its function in the HS response. Collectively, our data reveal a role for SUMOylation in the maintenance of DREB2A stability under high temperature, thus improving our understanding of the regulatory mechanisms underlying HS response in plant cells.




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SCFTIR1/AFB Auxin Signaling for Bending Termination during Shoot Gravitropism




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A Novel Role for a Phospholipase D in Plant Immunity




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MtSSPdb: A New Database for the Small Secreted Peptide Research Community




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Location, Location, Location: Phototropin 2 Action at the Chloroplast Membrane




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Phosphoregulation within the Photorespiratory Cycle: Regulate Smarter, Adapt Better?




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What Are the Roles for Dehydroascorbate Reductases and Glutathione in Sustaining Ascorbate Accumulation?




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Gibberellin Signaling in Plants: Entry of a new MicroRNA Player




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EPSIN1 Contributes to Plant Immunity by Modulating the Abundance of Pattern Recognition Receptors at the Plasma Membrane




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Severe Pulmonary Hypertension Management Across Europe (PHAROS): an ERS Clinical Research Collaboration

The past 20 years have seen major advances in the understanding and treatment of pulmonary arterial hypertension (PAH; group 1 of the pulmonary hypertension (PH) clinical classification) [1]. A strong basis of knowledge has been acquired in: 1) large randomised clinical trials for drug development; 2) national registries for epidemiology and outcome; and 3) smaller studies on the pathophysiological mechanisms of the disease. This knowledge has been reviewed at World Symposia on Pulmonary Hypertension (the most recent in 2018 [2]) and summarised in European Respiratory Society (ERS)/European Society of Cardiology (ESC) clinical guidelines (the most recent in 2015 [3, 4]). We are, however, much less knowledgeable on specific aspects such as 1) the implementation of guidelines and access to therapies in different European countries; 2) the management of PH crises and progressive (acute on chronic) heart failure; and 3) other groups of PH, such as PH due to lung diseases. Therapeutic strategies also need to be optimised, in particular regarding the combination of drugs, the use of anticoagulants, the place for new medications targeting different pathophysiological pathways, etc.




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Inhaled corticosteroids and COVID-19: a systematic review and clinical perspective

The current coronavirus 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection, raises important questions as to whether pre-morbid use or continued administration of inhaled corticosteroids (ICS) affects the outcomes of acute respiratory infections due to coronavirus. Many physicians are concerned about whether individuals positive for SARS-CoV-2 and taking ICS should continue them or stop them, given that ICS are often regarded as immunosuppressive. A number of key questions arise. Are people with asthma or COPD at increased risk of developing COVID-19? Do ICS modify this risk, either increasing or decreasing it? Do ICS influence the clinical course of COVID-19? (figure 1). Whether ICS modify the risk of developing COVID-19 or the clinical course of COVID-19 in people who do not have lung disease should also be considered (figure 1).




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Looking back to go forward: adherence to inhaled therapy before biologic therapy in severe asthma

For decades inhaled corticosteroids have been central to the management of asthma and are proven to be effective in maintaining symptom control, reducing exacerbations and preserving quality of life through mediation of airway inflammation. However, a small minority of patients have disease which is refractory to high dose inhaled corticosteroid (ICS) therapy and require additional oral corticosteroids to achieve acceptable control of symptoms and exacerbations. Severe asthma represents less than 10% of the total asthma population [1] but is the most serious, life-affecting and costly form of the condition [2].




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A clinically significant bronchodilator response in children: how should it be measured?

We thank F. Guezguez and H. Ben Saad for raising important questions on recommendations for assessing a bronchodilator response (BDR) in children. The authors summarise how recommended outcome measures and cut-offs for BDR in children vary between guidelines, and raise questions about our study [1].




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Bronchopulmonary dysplasia: a crime of opportunity?

First described in 1967, one of the most vexing problems in the care of preterm infants continues to be bronchopulmonary dysplasia (BPD). The clinical presentation and pathological changes associated with BPD, also referred to as chronic lung disease of prematurity, have changed substantially since that initial description by Northway et al. [1]. The condition described in that seminal report, characterised by marked respiratory distress associated with pulmonary oedema due to shunting across the patent ductus arteriosus, was also specific to preterm infants that had received high inspired oxygen concentrations for at least a week.




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Predictors of mortality for patients with COVID-19 pneumonia caused by SARS-CoV-2: a prospective cohort study

The aim of this study was to identify factors associated with the death of patients with COVID-19 pneumonia caused by the novel coronavirus SARS-CoV-2.

All clinical and laboratory parameters were collected prospectively from a cohort of patients with COVID-19 pneumonia who were hospitalised to Wuhan Pulmonary Hospital (Wuhan City, Hubei Province, China) between 25 December 2019 and 7 February 2020. Univariate and multivariate logistic regression was performed to investigate the relationship between each variable and the risk of death of COVID-19 pneumonia patients.

In total, 179 patients with COVID-19 pneumonia (97 male and 82 female) were included in the present prospective study, of whom 21 died. Univariate and multivariate logistic regression analysis revealed that age ≥65 years (OR 3.765, 95% CI 1.146-17.394; p=0.023), pre-existing concurrent cardiovascular or cerebrovascular diseases (OR 2.464, 95% CI 0.755-8.044; p=0.007), CD3+CD8+ T-cells ≤75 cells·μL–1 (OR 3.982, 95% CI 1.132-14.006; p<0.001) and cardiac troponin I ≥0.05 ng·mL–1 (OR 4.077, 95% CI 1.166-14.253; p<0.001) were associated with an increase in risk of mortality from COVID-19 pneumonia. In a sex-, age- and comorbid illness-matched case–control study, CD3+CD8+ T-cells ≤75 cells·μL–1 and cardiac troponin I ≥0.05 ng·mL–1 remained as predictors for high mortality from COVID-19 pneumonia.

We identified four risk factors: age ≥65 years, pre-existing concurrent cardiovascular or cerebrovascular diseases, CD3+CD8+ T-cells ≤75 cells·μL–1 and cardiac troponin I ≥0.05 ng·mL–1. The latter two factors, especially, were predictors for mortality of COVID-19 pneumonia patients.




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No association of COVID-19 transmission with temperature or UV radiation in Chinese cities

The coronavirus disease 2019 (COVID-19) epidemic, which was first reported in December 2019 in Wuhan, China, has caused 80 904 confirmed cases as of 9 March 2020, with 28 673 cases being reported outside of China. It has been declared a pandemic by the World Health Organization (WHO), has exhibited human-to-human transmissibility and has spread rapidly across countries [1]. Although the Chinese government has taken various measures to control city-to-city transmission (e.g. shutting down cities, extending holidays) and many other countries have implemented measures (such as airport screening and testing patients who have reported symptoms), the number of cases is still increasing quickly throughout the world.




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What constitutes a "clinically significant" bronchodilator response in children?

We read with great interest the recent paper of de Jong et al. [1] evaluating the contribution of a detailed history and a variety of diagnostic tests, including spirometry and bronchodilator tests, to diagnosing asthma in 111 children. In the methodology section, with regard to their definition of a "clinically significant" bronchodilator responsiveness (BDR), the authors only considered the forced expiratory volume in 1 s (FEV1) and applied the following two thresholds: ≥10% increase (no reference was cited) and ≥12% increase (according to the National Institute for Health and Care Excellence (NICE) [2]). Their approach could be a source of confusion for at least three reasons.




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Adherence to corticosteroids and clinical outcomes in mepolizumab therapy for severe asthma

Introduction

Inhaled corticosteroids (ICS) achieve disease control in the majority of asthmatic patients, although adherence to prescribed ICS is often poor. Patients with severe eosinophilic asthma may require treatment with oral corticosteroids (OCS) and/or biologic agents such as mepolizumab. It is unknown if ICS adherence changes on, or alters clinical response to, biologic therapy.

Methods

We examined ICS adherence and clinical outcomes in OCS-dependent severe eosinophilic asthma patients who completed 1 year of mepolizumab therapy. The ICS medicines possession ratio (MPR) was calculated (the number of doses of ICS issued on prescription/expected number) for the year before and the year after biologic initiation. Good adherence was defined as MPR >0.75, intermediate 0.74–0.51 and poor <0.5. We examined outcomes after 12 months of biologic therapy, including OCS reduction and annualised exacerbation rate (AER), stratified by adherence to ICS on mepolizumab.

Results

Out of 109 patients commencing mepolizumab, 91 who had completed 12 months of treatment were included in the final analysis. While receiving mepolizumab, 68% had good ICS adherence, with 16 (18%) having poor ICS adherence. ICS use within the cohort remained similar before (MPR 0.81±0.32) and during mepolizumab treatment (0.82±0.32; p=0.78). Patients with good adherence had greater reductions in OCS dose (median (interquartile range) OCS reduction 100 (74–100)% versus 60 (27–100)%; p=0.031) and exacerbations (AER change –2.1±3.1 versus 0.3±2.5; p=0.011) than those with poor adherence. Good ICS adherence predicted the likelihood of stopping maintenance OCS (adjusted OR 3.19, 95% CI 1.02–9.94; p=0.045).

Conclusion

ICS nonadherence is common in severe eosinophilic asthma patients receiving mepolizumab, and is associated with a lesser reduction in OCS requirements and AER.




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Therapeutic drug monitoring using saliva as matrix: an opportunity for linezolid, but challenge for moxifloxacin

The World Health Organization (WHO) has listed moxifloxacin and linezolid among the preferred "group A" drugs in the treatment of multidrug-resistant (MDR)-tuberculosis (TB) [1]. Therapeutic drug monitoring (TDM) could potentially optimise MDR-TB therapy, since moxifloxacin and linezolid show large pharmacokinetic variability [1–4]. TDM of moxifloxacin focuses on identifying patients with low drug exposure who are at risk of treatment failure and acquired fluoroquinolone resistance [5, 6]. Alternatively, TDM of linezolid strives to reduce toxicity while ensuring an adequate drug exposure because of its narrow therapeutic index [1, 3, 7].




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Forced oscillation technique for optimising PEEP in ventilated extremely preterm infants

Ventilatory settings are critical in mechanically ventilated extremely preterm newborn infants due to the risk of ventilation-induced lung injury (VILI) and the subsequent development of bronchopulmonary dysplasia (BPD) [1]. Positive end-expiratory pressure (PEEP) settings usually rely on blood gases, oxygen requirement, lung auscultation, evaluation of chest radiograph and assessment of the pressure/volume curves provided by ventilators. Studies of optimal PEEP settings in the surfactant-treated preterm infant in need of mechanical ventilation are limited and evidence-based clinical guidelines are sparse [2, 3]. A bedside method identifying the PEEP value that comprises maximal lung volume recruitment and minimising tissue overdistension could improve real-time optimisation of PEEP and potentially minimise the risk of VILI and BPD [4, 5].




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European Respiratory Journal




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Apraxia of speech involves lesions of dorsal arcuate fasciculus and insula in patients with aphasia

Objective

To determine the contributions of apraxia of speech (AOS) and anomia to conversational dysfluency.

Methods

In this observational study of 52 patients with chronic aphasia, 47 with concomitant AOS, fluency was quantified using correct information units per minute (CIUs/min) from propositional speech tasks. Videos of patients performing conversational, how-to and picture-description tasks, word and sentence repetition, and diadochokinetic tasks were used to diagnose AOS using the Apraxia of Speech Rating Scale (ASRS). Anomia was quantified by patients' scores on the 30 even-numbered items from the Boston Naming Test (BNT).

Results

Together, ASRS and BNT scores accounted for 51.4% of the total variance in CIUs/min; the ASRS score accounted for the majority of that variance. The BNT score was associated with lesions in the left superior temporal gyrus, left inferior frontal gyrus, and large parts of the insula. The global ASRS score was associated with lesions in the left dorsal arcuate fasciculus (AF), pre- and post-central gyri, and both banks of the central sulcus of the insula. The ASRS score for the primary distinguishing features of AOS (no overlap with features of aphasia) was associated with less AF and more insular involvement. Only ~27% of this apraxia-specific lesion overlapped with lesions associated with the BNT score. Lesions associated with AOS had minimal overlap with the frontal aslant tract (FAT) (<1%) or the extreme capsule fiber tract (1.4%). Finally, ASRS scores correlated significantly with damage to the insula but not to the AF, extreme capsule, or FAT.

Conclusions

Results are consistent with previous findings identifying lesions of the insula and AF in patients with AOS, damage to both of which may create dysfluency in patients with aphasia.




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Neurology consults in emergency departments: Opportunities to streamline care

Objective

To use the variations in neurology consultations requested by emergency department (ED) physicians to identify opportunities to implement multidisciplinary interventions in an effort to reduce ED overcrowding.

Methods

We retrospectively analyzed ED visits across 3 urban hospitals to determine the top 10 most common chief complaints leading to neurology consultation. For each complaint, we evaluated the likelihood of consultation, admission rate, admitting services, and provider-to-provider variability of consultation.

Results

Of 145,331 ED encounters analyzed, 3,087 (2.2%) involved a neurology consult, most commonly with chief complaints of acute-onset neurologic deficit, subacute neurologic deficit, or altered mental status. ED providers varied most in their consultation for acute-onset neurologic deficit, dizziness, and headache. Neurology consultation was associated with a 2.3-hour-longer length of stay (LOS) (95% CI: 1.6–3.1). Headache in particular has an average of 6.7-hour-longer ED LOS associated with consultation, followed by weakness or extremity weakness (4.4 hours) and numbness (4.1 hours). The largest estimated cumulative difference (number of patients with the specific consultation multiplied by estimated difference in LOS) belongs to headache, altered mental status, and seizures.

Conclusion

A systematic approach to identify variability in neurology consultation utilization and its effect on ED LOS helps pinpoint the conditions most likely to benefit from protocolized pathways.




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Worldwide survey of neurologists on approach to autoimmune encephalitis

Objective

To explore practice differences in the diagnosis and management of autoimmune encephalitis (AE), which is complicated by issues with sensitivity/specificity of antibody testing, nonspecific MRI/EEG/CSF findings, and competing differential diagnoses.

Methods

We used a worldwide electronic survey with practice-related demographic questions and clinical questions about 2 cases: (1) a 20-year-old woman with a neuropsychiatric presentation strongly suspicious of AE and (2) a 40-year-old man with new temporal lobe seizures and cognitive impairment. Responses among different groups were compared using multivariable logistic regression.

Results

We received 1,333 responses from 94 countries; 12.0% identified as neuroimmunologists. Case 1: those treating >5 AE cases per year were more likely to send antibodies in both serum and CSF (adjusted odds ratio [aOR] vs 0 per year: 3.29, 95% CI 1.31–8.28, p = 0.011), pursue empiric immunotherapy (aOR: 2.42, 95% CI 1.33–4.40, p = 0.004), and continue immunotherapy despite no response and negative antibodies at 2 weeks (aOR: 1.65, 95% CI 1.02–2.69, p = 0.043). Case 2: neuroimmunologists were more likely to send antibodies in both serum and CSF (aOR: 1.80, 95% CI 1.12–2.90, p = 0.015). Those seeing >5 AE cases per year (aOR: 1.86, 95% CI 1.22–2.86, p = 0.004) were more likely to start immunotherapy without waiting for antibody results.

Conclusions

Our results highlight the heterogeneous management of AE. Neuroimmunologists and those treating more AE cases generally take a more proactive approach to testing and immunotherapy than peers. Results highlight the need for higher-quality cohorts and trials to guide empiric immunotherapy, and evidence-based guidelines aimed at both experts and nonexperts. Because the average AE patient is unlikely to be first seen by a neuroimmunologist, ensuring greater uniformity in our approach to suspected cases is essential to ensure that patients are appropriately managed.




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Factors associated with 30-day readmission for patients hospitalized for seizures

Background

We sought to determine the cumulative incidence of readmissions after a seizure-related hospitalization and identify risk factors and readmission diagnoses.

Methods

We performed a retrospective cohort study of adult patients hospitalized with a primary discharge diagnosis of seizure (International Classification of Diseases, Ninth Edition, Clinical Modification codes 345.xx and 780.3x) using the State Inpatient Databases across 11 states from 2009 to 2012. Hospital and community characteristics were obtained from the American Hospital Association and Robert Wood Johnson Foundation. We performed logistic regressions to explore effects of patient, hospital, and community factors on readmissions within 30 days of discharge.

Results

Of 98,712 patients, 13,929 (14%) were readmitted within 30 days. Reasons for readmission included epilepsy/convulsions (30% of readmitted patients), mood disorders (5%), schizophrenia (4%), and septicemia (4%). The strongest predictors of readmission were diagnoses of CNS tumor (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.9–2.4) or psychosis (OR 1.8, 95% CI 1.7–1.8), urgent index admission (OR 2.0, 95% CI 1.8–2.2), transfer to nonacute facilities (OR 1.7, 95% CI 1.6–1.8), long length of stay (OR 1.7, 95% CI 1.6–1.8), and for-profit hospitals (OR 1.7, 95% CI 1.6–1.8). Our main model's c-statistic was 0.66. Predictors of readmission for status epilepticus included index admission for status epilepticus (OR 3.5, 95% CI 2.6–4.7), low hospital epilepsy volume (OR 0.4, 95% CI 0.3–0.7), and rural hospitals (OR 4.8, 95% CI 2.1–10.9).

Conclusion

Readmission is common after hospitalization for seizures. Prevention strategies should focus on recurrent seizures, the most common readmission diagnosis. Many factors were associated with readmission, although readmissions remain challenging to predict.




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Risk of stroke after emergency department visits for neurologic complaints

Objective

To assess the risk of subsequent stroke among older patients discharged from an emergency department (ED) without a diagnosis of TIA or stroke.

Methods

Using electronic health record data from a large urban, university hospital and a community-based hospital, we analyzed patients aged 60–89 years discharged to home from the ED without an International Statistical Classification of Diseases and Related Health Problems, 9th or 10th Revision diagnosis of TIA or stroke. Based on the presence/absence of a head CT and the presence/absence of a chief complaint suggestive of TIA or stroke ("symptoms") during the index ED visit, we created 4 mutually exclusive groups (group 1, reference: head CT no, symptoms no; group 2: head CT no, symptoms yes; group 3: head CT yes, symptoms no; and group 4: head CT yes, symptoms yes). We calculated rates of stroke in the 30, 90, and 365 days after the index visit and used multivariable logistic regression to estimate odds ratios (ORs) for subsequent stroke.

Results

Among 35,622 patients (mean age 70 years, 59% women, and 16% African American), unadjusted rates of stroke in 365 days were as follows: group 4: 2.5%; group 3: 1.1%; group 2: 0.69%; and group 1: 0.54%. The adjusted OR for stroke was 3.30 (95% confidence interval [CI], 1.61–6.76) in group 4, 1.56 (95% CI, 1.16–2.09) in group 3, and 0.61 (95% CI, 0.22–1.67) in group 2.

Conclusions

Among patients discharged from the ED without a diagnosis of TIA or stroke, the occurrence of a head CT and/or specific neurologic symptoms established a clinically meaningful risk gradient for subsequent stroke.




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Machine learning as a diagnostic decision aid for patients with transient loss of consciousness

Background

Transient loss of consciousness (TLOC) is a common reason for presentation to primary/emergency care; over 90% are because of epilepsy, syncope, or psychogenic non-epileptic seizures (PNES). Misdiagnoses are common, and there are currently no validated decision rules to aid diagnosis and management. We seek to explore the utility of machine-learning techniques to develop a short diagnostic instrument by extracting features with optimal discriminatory values from responses to detailed questionnaires about TLOC manifestations and comorbidities (86 questions to patients, 31 to TLOC witnesses).

Methods

Multi-center retrospective self- and witness-report questionnaire study in secondary care settings. Feature selection was performed by an iterative algorithm based on random forest analysis. Data were randomly divided in a 2:1 ratio into training and validation sets (163:86 for all data; 208:92 for analysis excluding witness reports).

Results

Three hundred patients with proven diagnoses (100 each: epilepsy, syncope and PNES) were recruited from epilepsy and syncope services. Two hundred forty-nine completed patient and witness questionnaires: 86 epilepsy (64 female), 84 PNES (61 female), and 79 syncope (59 female). Responses to 36 questions optimally predicted diagnoses. A classifier trained on these features classified 74/86 (86.0% [95% confidence interval 76.9%–92.6%]) of patients correctly in validation (100 [86.7%–100%] syncope, 85.7 [67.3%–96.0%] epilepsy, 75.0 [56.6%–88.5%] PNES). Excluding witness reports, 34 features provided optimal prediction (classifier accuracy of 72/92 [78.3 (68.4%–86.2%)] in validation, 83.8 [68.0%–93.8%] syncope, 81.5 [61.9%–93.7%] epilepsy, 67.9 [47.7%–84.1%] PNES).

Conclusions

A tool based on patient symptoms/comorbidities and witness reports separates well between syncope and other common causes of TLOC. It can help to differentiate epilepsy and PNES. Validated decision rules may improve diagnostic processes and reduce misdiagnosis rates.

Classification of evidence

This study provides Class III evidence that for patients with TLOC, patient and witness questionnaires discriminate between syncope, epilepsy and PNES.




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Diagnosing spells: Machines or humans?

In the current era of technological advances in medicine, public interest seems focused on advances in laboratory testing, imaging, and surgical instrumentation. Modern-day expectations in the diagnostic part of medicine appear to demand answers which are instant, specific, and without ambiguity. This is consistent with the idea of developing the science of medicine. However, many still consider obtaining a diagnosis through a careful and thoughtful history as an example of the art of medicine.




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Author response: Functional neurologic disorders: Bringing the informal and hidden curriculum to light

Dr. Sethi raises an excellent point about the term functional neurologic disorder (FND) in his comment on the editorial.1 It seems clear that reticence to use the term functional creates the ambiguity he mentions. Medically unexplained symptoms, categorized in the international classification of diseases as undifferentiated somatoform disorders, are a diagnosis that many providers are loathed to give. Whether that is because of concern about missing a diagnosis is not clear. Having evaluated and treated more than 400 of these individuals in the FND clinic at the University of Colorado, I can attest to the fact that patients arrive confused about their diagnosis. Multiple incorrect diagnoses, as Dr. Sethi points out, pack the medical histories of patients with FND, leading doctors and patients astray. I believe that the commentary by Perez et al.2 gives us the best chance for a way forward, by teaching a new generation of residents and fellows how to approach patients in a nonjudgmental and open-minded fashion. It took 30 years to add Functional Neurologic Disorder to the Diagnostic and Statistical Manual, and it is still parenthetical to the term Conversion.3 Stripping the diagnosis of FND of its stigma and empowering care providers to rule in functional disorders is an actionable step which should be taken.




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Reader response: Functional neurologic disorders: Bringing the informal and hidden curriculum to light

I read with interest the editorial by Strom1 about functional neurologic disorders (FNDs). As a treating physician, I have struggled with the multiple diagnostic labels attached to these patients by physicians of different medical specialties during the course of their clinical disease presentation. A neurologist may assign a patient who presents with chronic fatigue the diagnostic labels of narcolepsy, idiopathic hypersomnia, or chronic Lyme disease. A rheumatologist may assign the label of collagen vascular disease, and a psychiatrist may diagnose depression. This diagnostic ambiguity is troublesome for patients and clinicians alike. I contend that even the term FND needs to be revisited. A patient should be broadly labeled as having a functional disorder and only after characterization sublabeled and referred to an appropriate specialty physician.




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Author response: Symptom burden among individuals with Parkinson disease: A national survey

We appreciate the readers' comments on the prevalence and impact of apathy on quality of life among individuals with Parkinson disease. In constructing our survey instrument, we discussed the inclusion of apathy as a symptom. However, we ultimately opted against inclusion because of concerns about the specificity of terminology in our online survey. Patients and care partners may not be familiar with the term "apathy,"and near-synonyms such as "reduced motivation" have substantial overlap with other nonmotor features. Still, as the readers point out, apathy is extremely common and under-recognized. Similar to many of the nonmotor symptoms identified in our study,1 we agree that clinicians should be screening for apathy among those with Parkinson disease.




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Unusual and important cause of acute neck pain: Longus colli calcific tendinitis

Early recognition of longus colli calcific tendinitis can prevent unnecessary interventions including antibiotics and surgical procedures.




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Initial Resuscitation Algorithm for Children




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Providing Care for Infants Born at Home

The American Academy of Pediatrics (AAP) believes that current data show that hospitals and accredited birth centers are the safest settings for birth in the United States. The AAP does not recommend planned home birth, which has been reported to be associated with a twofold to threefold increase in infant mortality in the United States. The AAP recognizes that women may choose to plan a home birth. This statement is intended to help pediatricians provide constructive, informed counsel to women considering home birth while retaining their role as child advocates and to summarize appropriate care for newborn infants born at home that is consistent with care provided for infants born in a medical care facility. Regardless of the circumstances of his or her birth, including location, every newborn infant deserves health care consistent with that highlighted in this statement, which is more completely described in other publications from the AAP, including Guidelines for Perinatal Care and the Textbook of Neonatal Resuscitation. All health care clinicians and institutions should promote communications and understanding on the basis of professional interaction and mutual respect.




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Children With Intellectual and Developmental Disabilities as Organ Transplantation Recipients

The demand for transplantable solid organs far exceeds the supply of deceased donor organs. Patient selection criteria are determined by individual transplant programs; given the scarcity of solid organs for transplant, allocation to those most likely to benefit takes into consideration both medical and psychosocial factors. Children with intellectual and developmental disabilities have historically been excluded as potential recipients of organ transplants. When a transplant is likely to provide significant health benefits, denying a transplant to otherwise eligible children with disabilities may constitute illegal and unjustified discrimination. Children with intellectual and developmental disabilities should not be excluded from the potential pool of recipients and should be referred for evaluation as recipients of solid organ transplants.




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Ames SG, Davis BS, Marin JR, L. Fink EL, Olson LM, Gausche-Hill M, Kahn JM. Emergency Department Pediatric Readiness and Mortality in Critically Ill Children. Pediatrics. 2019;144(3):e20190568




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Early and Often: The Need for Comprehensive Discussion of Treatment-Induced Cancer Late Effects




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Ahmed A, Fend PI, Gaensbauer JT, Reves RR, Khurana R, Salcedo K, Punnoose R, Katz DJ, for the TUBERCULOSIS EPIDEMIOLOGIC STUDIES CONSORTIUM. Interferon-{gamma} Release Assays in Children <15 Years of Age. Pediatrics. 2020:145(1):e20191930




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The Time Is Now: Standardized Sedation Training for Pediatric Hospitalists




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Exploring Early Childhood Factors as an Avenue to Address Chronic Peer Victimization




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Every Child Counts: The Importance of the 2020 Census for Pediatric Health Equity