Schwann cell-secreted PGE2 promotes sensory neuron excitability during development.

Electrical excitability-the ability to fire and propagate action potentials-is a signature feature of neurons. How neurons become excitable during development and whether excitability is an intrinsic property of neurons remain unclear. Here, we demonstrate that Schwann cells, the most abundant glia in the peripheral nervous system, promote somatosensory neuron excitability during development. We find that Schwann cells secrete prostaglandin E2, which is necessary and sufficient to induce developing somatosensory neurons to express normal levels of genes required for neuronal function, including voltage-gated sodium channels, and to fire action potential trains. Inactivating this signaling pathway in Schwann cells impairs somatosensory neuron maturation, causing multimodal sensory defects that persist into adulthood. Collectively, our studies uncover a neurodevelopmental role for prostaglandin E2 distinct from its established role in inflammation, revealing a cell non-autonomous mechanism by which glia regulate neuronal excitability to enable the development of normal sensory functions.

An alphacoronavirus polymerase structure reveals conserved replication factor functions.

Coronaviruses are a diverse subfamily of viruses containing pathogens of humans and animals. This subfamily of viruses replicates their RNA genomes using a core polymerase complex composed of viral non-structural proteins: nsp7, nsp8 and nsp12. Most of our understanding of coronavirus molecular biology comes from betacoronaviruses like SARS-CoV and SARS-CoV-2, the latter of which is the causative agent of COVID-19. In contrast, members of the alphacoronavirus genus are relatively understudied despite their importance in human and animal health. Here we have used cryo-electron microscopy to determine structures of the alphacoronavirus porcine epidemic diarrhea virus (PEDV) core polymerase complex bound to RNA. One structure shows an unexpected nsp8 stoichiometry despite remaining bound to RNA. Biochemical analysis shows that the N-terminal extension of one nsp8 is not required for in vitro RNA synthesis for alpha- and betacoronaviruses. Our work demonstrates the importance of studying diverse coronaviruses in revealing aspects of coronavirus replication and identifying areas of conservation to be targeted by antiviral drugs.

A genus-specific nsp12 region impacts polymerase assembly in Alphacoronavirus and Gammacoronavirus.

Coronavirus relevancy for human health has surged over the past 20 years as they have a propensity for spillover into humans from animal reservoirs resulting in pandemics such as COVID-19. The diversity within the Coronavirinae subfamily and high infection frequency in animal species worldwide creates a looming threat that calls for research across all genera within the Coronavirinae subfamily. We sought to contribute to the limited structural knowledge within the Gammacoronavirus genera and determined the structure of the viral core replication-transcription complex (RTC) from infectious bronchitis virus using single-particle cryo-electron microscopy. Comparison between our infectious bronchitis virus structure with published RTC structures from other Coronavirinae genera reveals structural differences across genera. Using in vitro biochemical assays, we characterized these differences and revealed their differing involvement in core RTC formation across different genera. Our findings highlight the value of cross-genera Coronavirinae studies, as they show genera-specific features in coronavirus genome replication. A broader knowledge of coronavirus replication will better prepare us for future coronavirus spillovers.

Interfering with nucleotide excision by the coronavirus 3'-to-5' exoribonuclease.

Some of the most efficacious antiviral therapeutics are ribonucleos(t)ide analogs. The presence of a 3'-to-5' proofreading exoribonuclease (ExoN) in coronaviruses diminishes the potency of many ribonucleotide analogs. The ability to interfere with ExoN activity will create new possibilities for control of SARS-CoV-2 infection. ExoN is formed by a 1:1 complex of nsp14 and nsp10 proteins. We have purified and characterized ExoN using a robust, quantitative system that reveals determinants of specificity and efficiency of hydrolysis. Double-stranded RNA is preferred over single-stranded RNA. Nucleotide excision is distributive, with only one or two nucleotides hydrolyzed in a single binding event. The composition of the terminal basepair modulates excision. A stalled SARS-CoV-2 replicase in complex with either correctly or incorrectly terminated products prevents excision, suggesting that a mispaired end is insufficient to displace the replicase. Finally, we have discovered several modifications to the 3'-RNA terminus that interfere with or block ExoN-catalyzed excision. While a 3'-OH facilitates hydrolysis of a nucleotide with a normal ribose configuration, this substituent is not required for a nucleotide with a planar ribose configuration such as that present in the antiviral nucleotide produced by viperin. Design of ExoN-resistant, antiviral ribonucleotides should be feasible.

The association of intraoperative opioid dose with postanesthesia care unit outcomes in children: a retrospective study.

PURPOSE: In children, the relationship between the dose of intraoperative opioid and postoperative outcomes is unclear. We examined the relationship between intraoperative opioid dose and postanesthesia care unit (PACU) pain scores and opioid and antiemetic administrations. METHODS: We performed a single-institution retrospective cohort study. Patients who were aged < 19 yr, had an American Society of Anesthesiologists Physical Status of I-III, were undergoing one of 11 procedures under general anesthesia and without regional anesthesia, and who were admitted to the PACU were included. Patients were analyzed by quartiles of total intraoperative opioid dose using multivariable regression, adjusting for confounders including procedure. An exploratory analysis of opioid-free anesthetics was also performed. RESULTS: Three thousand, seven hundred and thirty-three cases were included, and the mean age of included patients was 8.3 yr. After adjustment, there were no significant differences between the lowest and higher quartiles for first conscious pain score, mean pain score, PACU opioid dose, or PACU length of stay; in addition, estimated differences were small. Patients in higher quartiles were estimated to be more likely to receive antiemetics, significantly so for those in the second quartile. Patients in the lowest quartile received significantly more intraoperative nonopioid analgesics. In the exploratory analysis, no significant difference in PACU pain scores was found in cases without intraoperative opioids. CONCLUSIONS: Children who received lower doses of intraoperative opioids did not have worse PACU pain outcomes but required fewer antiemetics and received greater numbers of nonopioid analgesics intraoperatively. These findings suggest that lower doses of intraoperative opioids may be administered to children as long as other analgesics are used.

RéSUMé: OBJECTIF: Chez les enfants, la relation entre la dose peropératoire d'opioïdes et les issues postopératoires n'est pas claire. Nous avons examiné la relation entre la dose peropératoire d'opioïdes, les scores de douleur en salle de réveil, et les administrations d'opioïdes et d'antiémétiques. MéTHODE: Nous avons réalisé une étude de cohorte rétrospective dans un seul établissement. Nous avons inclus les patient·es âgé·es < 19 ans ayant un statut physique ASA de I-III et bénéficiant de l'une de 11 interventions sous anesthésie générale et sans anesthésie régionale, et qui avaient été admis·es en salle de réveil. Les patient·es ont été analysé·es par quartiles de la dose totale d'opioïdes peropératoires en utilisant une régression multivariée, en ajustant les données pour tenir compte des facteurs de confusion, notamment de l'intervention. Une analyse exploratoire des anesthésiques sans opioïdes a également été réalisée. RéSULTATS: Au total 3733 cas ont été inclus, et l'âge moyen des enfants était de 8,3 ans. Après ajustement, il n'y avait pas de différences significatives entre les quartiles inférieur et supérieur pour le premier score de douleur chez l'enfant conscient·e, le score de douleur moyen, la dose d'opioïdes en salle de réveil ou la durée du séjour en salle de réveil; de plus, les différences estimées étaient faibles. On a estimé que les patient·es des quartiles supérieurs étaient plus susceptibles de recevoir des antiémétiques et ce, de manière significative pour ceux et celles du deuxième quartile. Les patient·es du quartile inférieur ont reçu significativement plus d'analgésiques non opioïdes peropératoires. Dans l'analyse exploratoire, aucune différence significative dans les scores de douleur en salle de réveil n'a été trouvée dans les cas sans opioïdes peropératoires. CONCLUSION: Les enfants qui ont reçu des doses plus faibles d'opioïdes peropératoires n'ont pas eu de pires issues de douleur en salle de réveil, mais ont eu besoin de moins d'antiémétiques et ont reçu un plus grand nombre d'analgésiques non opioïdes en peropératoire. Ces résultats suggèrent que des doses plus faibles d'opioïdes peropératoires peuvent être administrées aux enfants tant que d'autres analgésiques sont utilisés.

A randomized comparison of an adhesive gelatin sponge and a plain collagen sponge for hemostatic control during canine liver surgery.

OBJECTIVE: To compare the effectiveness of a modified surface gelatin sponge to a plain collagen sponge for hemostasis of parenchymal hepatic bleeding. STUDY DESIGN: Prospective, randomized trial of two hemostatic agents. ANIMALS: A total of 45 dogs undergoing elective liver surgery were randomly allocated into two groups: 22 in the adhesive gelatin (AG) group and 23 in the plain collagen (PC) group. A total of 20 patients per group underwent liver biopsy to create a uniformly sized bleeding surface, with the remaining patients (AG = 2, PC = 3) undergoing liver lobectomy. METHODS: Evaluation of hemostatic effectiveness and tissue adhesion of each sponge type was performed by the operating surgeon using structured scoring systems. Hemostatic parameters were primarily evaluated at the liver biopsy site to maintain homogeneity of bleeding surface size. RESULTS: For the liver biopsy group (n = 40), 5 min after hemostatic sponge application, 10/20 dogs were bleeding in the PC group, compared to 2/20 in AG group (p = .0138). The PC bleeding was significantly higher than AG across the 3 to 6 min evaluation period (p < .001). When surgeons tested the adhesion of the sponge across the whole cohort (n = 45), AG scored 2 (of 3) against 1 for PC (p < .001). In group PC, 5/23 sponges dislodged during abdominal lavage and preparations for closure and had to be replaced due to recurrence of bleeding, compared with no AG sponges dislodging (p = .042). There were no further complications related to the use of either sponge. CONCLUSION: In the dogs with hepatic parenchymal incision, use of an adhesive gelatin sponge improved intraoperative attachment and haemostatic effectiveness, compared to a collagen sponge. CLINICAL SIGNIFICANCE: Based on our clinical experience in these cases, adhesive gelatin sponges could be considered an effective option when selecting a hemostatic agent for liver surgery in dogs.

Nailing distal tibial fractures: does entry technique affect distal alignment?

PURPOSE: In treating distal third tibial fractures, restoration of the axial alignment and therefore accurate reduction of the distal fragment minimise the risk of tibiotalar joint malalignment. The aim of this study is to investigate whether there was a difference in accuracy of reduction and axial alignment, when nailing distal third tibial fractures using either the suprapatellar or the infrapatellar tibial nailing entry technique. METHODS: This retrospective cohort study compared alignment of intramedullary nails performed for distal third tibial fractures between 2015 and 2018 through the suprapatellar and infrapatellar approach at a UK Level 1 trauma centre. It compared a consecutive series of 74 suprapatellar nails and 51 infrapatellar nails, with radiographic assessment of tibial alignment in the antero-posterior and sagittal planes. It included inter- and intra-observer analyses of radiographic measurements. RESULTS: In the coronal plane, mean malalignment in the suprapatellar technique group was 2.8 ± 0.7° and 4.7 ± 0.9° in the infrapatellar technique group (P < 0.01). In the sagittal plane, mean malalignment in the suprapatellar technique group was 4.0 ± 0.8° and 3.5 ± 0.9° in the infrapatellar technique group (P = 0.42). Intra- and inter-observer analysis showed strongly positive correlations between observers. CONCLUSIONS: We suggest that the suprapatellar technique may improve coronal plane alignment when intramedullary nailing distal tibial fractures. There was no significant difference in alignment in the sagittal plane. We conclude that the suprapatellar technique may be superior in preventing malalignment when treating distal third tibial fractures, potentially improving clinical outcome.

Ocean carbon sequestration: Particle fragmentation by copepods as a significant unrecognised factor?: Explicitly representing the role of copepods in biogeochemical models may fundamentally improve understanding of future ocean carbon storage.

Ocean biology helps regulate global climate by fixing atmospheric CO2 and exporting it to deep waters as sinking detrital particles. New observations demonstrate that particle fragmentation is the principal factor controlling the depth to which these particles penetrate the ocean's interior, and hence how long the constituent carbon is sequestered from the atmosphere. The underlying cause is, however, poorly understood. We speculate that small, particle-associated copepods, which intercept and inadvertently break up sinking particles as they search for attached protistan prey, are the principle agents of fragmentation in the ocean. We explore this idea using a new marine ecosystem model. Results indicate that explicitly representing particle fragmentation by copepods in biogeochemical models offers a step change in our ability to understand the future evolution of biologically-mediated ocean carbon storage. Our findings highlight the need for improved understanding of the distribution, abundance, ecology and physiology of particle-associated copepods.

Diagnostic Point-of-Care Ultrasound: Recommendations From an Expert Panel.

Diagnostic point-of-care ultrasound (PoCUS) has emerged as a powerful tool to help anesthesiologists guide patient care in both the perioperative setting and the subspecialty arenas. Although anesthesiologists can turn to guideline statements pertaining to other aspects of ultrasound use, to date there remains little in the way of published guidance regarding diagnostic PoCUS. To this end, in 2018, the American Society of Anesthesiologists chartered an ad hoc committee consisting of 23 American Society of Anesthesiologists members to provide recommendations on this topic. The ad hoc committee convened and developed a committee work product. This work product was updated in 2021 by an expert panel of the ad hoc committee to produce the document presented herein. The document, which represents the consensus opinion of a group of practicing anesthesiologists with established expertise in diagnostic ultrasound, addresses the following issues: (1) affirms the practice of diagnostic PoCUS by adequately trained anesthesiologists, (2) identifies the scope of practice of diagnostic PoCUS relevant to anesthesiologists, (3) suggests the minimum level of training needed to achieve competence, (4) provides recommendations for how diagnostic PoCUS can be used safely and ethically, and (5) provides broad guidance about diagnostic ultrasound billing.

Biosynthesis of d-glycero-l-gluco-Heptose in the Capsular Polysaccharides of Campylobacter jejuni.

Campylobacter jejuni is the leading cause of food poisoning in the United States and Europe. The exterior cell surface of C. jejuni is coated with a capsular polysaccharide (CPS) that is essential for the maintenance and integrity of the bacterial cell wall and evasion of the host immune response. The identity and sequences of the monosaccharide components of the CPS are quite variable and dependent on the specific strain of C. jejuni. It is currently thought that the immediate precursor for the multiple variations found in the heptose moieties of the C. jejuni CPS is GDP-d-glycero-α-d-manno-heptose. In C. jejuni NCTC 11168, the heptose moiety is d-glycero-l-gluco-heptose. It has previously been shown that Cj1427 catalyzes the oxidation of GDP-d-glycero-α-d-manno-heptose to GDP-d-glycero-4-keto-α-d-lyxo-heptose using α-ketoglutarate as a cosubstrate. Cj1430 was now demonstrated to catalyze the double epimerization of this product at C3 and C5 to form GDP-d-glycero-4-keto-ß-l-xylo-heptose. Cj1428 subsequently catalyzes the stereospecific reduction of this GDP-linked heptose by NADPH to form GDP-d-glycero-ß-l-gluco-heptose. The three-dimensional crystal structure of Cj1430 was determined to a resolution of 1.85 Å in the presence of bound GDP-d-glycero-ß-l-gluco-heptose, a product analogue. The structure shows that it belongs to the cupin superfamily. The three-dimensional crystal structure of Cj1428 was solved in the presence of NADPH to a resolution of 1.50 Å. Its fold places it into the short-chain dehydrogenase/reductase superfamily. Typically, members in this family display a characteristic signature sequence of YXXXK, with the conserved tyrosine serving a key role in catalysis. In Cj1428, this residue is a phenylalanine.

Oligodendrocytes are susceptible to Zika virus infection in a mouse model of perinatal exposure: Implications for CNS complications.

Some children with proven intrauterine Zika virus (ZIKV) infection who were born asymptomatic subsequently manifested neurodevelopmental delays, pointing to impairment of development perinatally and postnatally. To model this, we infected postnatal day (P) 5-6 (equivalent to the perinatal period in humans) susceptible mice with a mammalian cell-propagated ZIKV clinical isolate from the Brazilian outbreak in 2015. All infected mice appeared normal up to 4 days post-intraperitoneal inoculation (dpi), but rapidly developed severe clinical signs at 5-6 dpi. All nervous tissue examined at 5/6 dpi appeared grossly normal. However, anti-ZIKV positive cells were observed in the optic nerve, brain, and spinal cord; predominantly in white matter. Co-labeling with cell type specific markers demonstrated oligodendrocytes and astrocytes support productive infection. Rarely, ZIKV positive neurons were observed. In spinal cord white matter, which we examined in detail, apoptotic cells were evident; the density of oligodendrocytes was significantly reduced; and there was localized microglial reactivity including expression of the NLRP3 inflammasome. Together, our observations demonstrate that a clinically relevant ZIKV isolate can directly impact oligodendrocytes. As primary oligodendrocyte cell death can lead later to secondary autoimmune demyelination, our observations may help explain neurodevelopmental delays in infants appearing asymptomatic at birth and commend lifetime surveillance.

Synchronous effects produce cycles in deer populations and deer-vehicle collisions.

Population cycles are fundamentally linked with spatial synchrony, the prevailing paradigm being that populations with cyclic dynamics are easily synchronised. That is, population cycles help give rise to spatial synchrony. Here we demonstrate this process can work in reverse, with synchrony causing population cycles. We show that timescale-specific environmental effects, by synchronising local population dynamics on certain timescales only, cause major population cycles over large areas in white-tailed deer. An important aspect of the new mechanism is specificity of synchronising effects to certain timescales, which causes local dynamics to sum across space to a substantial cycle on those timescales. We also demonstrate, to our knowledge for the first time, that synchrony can be transmitted not only from environmental drivers to populations (deer), but also from there to human systems (deer-vehicle collisions). Because synchrony of drivers may be altered by climate change, changes to population cycles may arise via our mechanism.

Demographic effects of phenological variation in natural populations of two pond-breeding salamanders.

Phenology is a key driver of population and community dynamics. Phenological metrics (e.g., first date that an event occurred) often simplify information from the full phenological distribution, which may undermine efforts to determine the importance of life history events. Data regarding full phenological distributions are especially needed as many species are shifting phenology with climatic change which can alter life-history patterns and species dynamics. We tested whether skewness, kurtosis or maximum duration of breeding phenology affected juvenile emigration phenology and survival in natural populations of ringed (Ambystoma annulatum) and spotted salamanders (A. maculatum) spanning a 7-year period at two study locations. We evaluated the relative importance of different phenological metrics in breeding phenology and larval density dependence on emigration phenology and survival. We found that variability in emigration phenology differed by species, with ringed salamanders having a shorter duration and distributions that were more often right-skewed and leptokurtic compared to spotted salamanders. Emigration phenology was not linked to any measure of variability in breeding phenology, indicating phenological variability operates independently across life stages and may be subject to stage-specific influences. Emigration duration and skewness were partially explained by larval density, which demonstrates how phenological distributions may change with species interactions. Further tests that use the full phenological distribution to link variability in timing of life history events to demographic traits such as survival are needed to determine if and how phenological shifts will impact species persistence.

Direct effects influence larval salamander size and density more than indirect effects.

Direct and indirect effects both influence population and community dynamics. The relative strengths of these pathways are often compared using experimental approaches, but their evaluation in situ has been less frequent. We examined how individual and aggregate impacts of direct and indirect effects of species densities, proxies for competition and predation pressure, and habitat variables influenced patterns of larval density and body size of ringed (Ambystoma annulatum) and spotted salamanders (A. maculatum). We surveyed > 150 ponds in Missouri, USA, from 2012 to 2014 to measure the density and body size of each focal species, the density of co-occurring pond food web members, and select habitat features. We used structural equation modeling to quantify the relative importance of direct and indirect pathways on both body size and larval density. Overall, both responses were explained through a combination of direct and indirect effects. However, the magnitudes of direct effects were often greater than indirect effects. Some of the direct and indirect relationships with larval salamander size and density were also consistent with results from experimental studies. Finally, total direct and indirect effects were often weaker due to habitat and density variables negating each other's impacts. Overall, our study shows that direct effects were equivalent to, or more important than, indirect effects. We also demonstrate that the effects stemming from individual relationships can sum to produce net patterns that are negligible in magnitude. Further work on direct and indirect effects with observational data are needed to examine their magnitudes in natural communities.

Publication misrepresentation among pediatric anesthesiology fellowship applicants: A retrospective single-center cohort study.

BACKGROUND: Many medical specialties have found publication misrepresentation in residency and fellowship applications, but pediatric anesthesia fellowship application data is lacking. AIMS: We sought to determine the prevalence of publication misrepresentation among pediatric anesthesia fellowship applications. METHODS: In this retrospective cohort study, fellowship applications to Stanford University's pediatric anesthesiology fellowship program from 2009 to 2019 were reviewed. Only peer-reviewed journal articles listed as accepted or published were included. Nine additional variables were collected: applicant age, gender, citizenship status, American vs. international medical school, public vs. private medical school, allopathic doctor versus osteopathic doctor, number of years between college and medical school, additional degrees, and application year. The primary outcome was the rate of publication misrepresentation, defined as peer-reviewed journal citations listed on the application that could not be verified or on which the applicant was not listed as an author. Secondary outcomes were the associations between publication misrepresentation and the additional collected variables. RESULTS: 1280 peer-reviewed journal publications from 877 applicants were reviewed. 3.4% of all citations listed as peer-reviewed journal articles were misrepresented and 9.0% of all applicants with at least 1 publication had ≥1 misrepresented publications. 30.2% of publications labelled "misrepresented" were located in our search of databases but did not have the applicant as an author, and 69.8% could not be located using the search databases. Only one of the 9 collected variables (public vs private medical school) was significantly associated with publication misrepresentation. CONCLUSIONS: In this single-center retrospective study, publication misrepresentation was found to occur in one out of 11 pediatric anesthesia fellowship applications with at least one publication. Since residency and fellowship applicant publications may be heavily weighted during the application process, programs may want to include additional inquiries into the accuracy of applicant publications.

Structural Analysis of Cj1427, an Essential NAD-Dependent Dehydrogenase for the Biosynthesis of the Heptose Residues in the Capsular Polysaccharides of Campylobacter jejuni.

Many strains of Campylobacter jejuni display modified heptose residues in their capsular polysaccharides (CPS). The precursor heptose was previously shown to be GDP-d-glycero-α-d-manno-heptose, from which a variety of modifications of the sugar moiety have been observed. These modifications include the generation of 6-deoxy derivatives and alterations of the stereochemistry at C3-C6. Previous work has focused on the enzymes responsible for the generation of the 6-deoxy derivatives and those involved in altering the stereochemistry at C3 and C5. However, the generation of the 6-hydroxyl heptose residues remains uncertain due to the lack of a specific enzyme to catalyze the initial oxidation at C4 of GDP-d-glycero-α-d-manno-heptose. Here we reexamine the previously reported role of Cj1427, a dehydrogenase found in C. jejuni NTCC 11168 (HS:2). We show that Cj1427 is co-purified with bound NADH, thus hindering catalysis of oxidation reactions. However, addition of a co-substrate, α-ketoglutarate, converts the bound NADH to NAD+. In this form, Cj1427 catalyzes the oxidation of l-2-hydroxyglutarate back to α-ketoglutarate. The crystal structure of Cj1427 with bound GDP-d-glycero-α-d-manno-heptose shows that the NAD(H) cofactor is ideally positioned to catalyze the oxidation at C4 of the sugar substrate. Additionally, the overall fold of the Cj1427 subunit places it into the well-defined short-chain dehydrogenase/reductase superfamily. The observed quaternary structure of the tetrameric enzyme, however, is highly unusual for members of this superfamily.

Nucleotide Analogues as Inhibitors of SARS-CoV-2 Polymerase, a Key Drug Target for COVID-19.

SARS-CoV-2 is responsible for the current COVID-19 pandemic. On the basis of our analysis of hepatitis C virus and coronavirus replication, and the molecular structures and activities of viral inhibitors, we previously demonstrated that three nucleotide analogues (the triphosphates of Sofosbuvir, Alovudine, and AZT) inhibit the SARS-CoV RNA-dependent RNA polymerase (RdRp). We also demonstrated that a library of additional nucleotide analogues terminate RNA synthesis catalyzed by the SARS-CoV-2 RdRp, a well-established drug target for COVID-19. Here, we used polymerase extension experiments to demonstrate that the active triphosphate form of Sofosbuvir (an FDA-approved hepatitis C drug) is incorporated by SARS-CoV-2 RdRp and blocks further incorporation. Using the molecular insight gained from the previous studies, we selected the active triphosphate forms of six other antiviral agents, Alovudine, Tenofovir alafenamide, AZT, Abacavir, Lamivudine, and Emtricitabine, for evaluation as inhibitors of the SARS-CoV-2 RdRp and demonstrated the ability of these viral polymerase inhibitors to be incorporated by SARS-CoV-2 RdRp, where they terminate further polymerase extension with varying efficiency. These results provide a molecular basis for inhibition of the SARS-CoV-2 RdRp by these nucleotide analogues. If sufficient efficacy of some of these FDA-approved drugs in inhibiting viral replication in cell culture is established, they may be explored as potential COVID-19 therapeutics.

Reconciliation of the carbon budget in the ocean's twilight zone.

Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink.

Utility of topical agents for radiation dermatitis and pain: a randomized clinical trial.

PURPOSE: Although topical agents are often provided during radiation therapy, there is limited consensus and evidence for their use prophylactically to prevent or reduce radiation dermatitis. METHODS: This was a multi-site, randomized, placebo-controlled, blinded study of 191 breast cancer patients to compare the prophylactic effectiveness of three topical agents (Curcumin, HPR Plus™, and Placebo) for reducing radiation dermatitis and associated pain. Patients applied the topical agent to their skin in the radiation area site three times daily starting the first day of radiation therapy (RT) until 1 week after RT completion. RESULTS: Of the 191 randomized patients, 171 patients were included in the final analyses (87.5% white females, mean age = 58 (range = 36-88)). Mean radiation dermatitis severity (RDS) scores did not significantly differ between study arms (Curcumin = 2.68 [2.49, 2.86]; HPR Plus™ = 2.64 [2.45, 2.82]; Placebo = 2.63 [2.44, 2.83]; p = 0.929). Logistic regression analyses showed that increased breast field separation positively correlated with increased radiation dermatitis severity (p = 0.018). In patients with high breast field separation (≥ 25 cm), RDS scores (Curcumin = 2.70 [2.21, 3.19]; HPR Plus™ = 3.57 [3.16, 4.00]; Placebo = 2.95 [2.60, 3.30]; p = 0.024) and pain scores (Curcumin = 0.52 [- 0.28, 1.33]; HPR Plus™ = 0.55 [- 0.19, 1.30]; Placebo = 1.73 [0.97, 2.50]; p = 0.046) significantly differed at the end of RT. CONCLUSIONS: Although there were no significant effects of the treatment groups on the overall population, our exploratory subgroup analysis suggests that prophylactic treatment with topical curcumin may be effective for minimizing skin reactions and pain for patients with high breast separation (≥ 25 cm) who may have the worst skin reactions.

Effects of high neuromuscular blocking agent dose on post-operative respiratory complications in infants and children.

BACKGROUND: This study evaluated the association between neuromuscular blocking agent dose and post-operative respiratory complications in infants and children. METHODS: Data from 6507 general anaesthetics provided to children aged 0-10 years undergoing surgery were analysed to examine the effects of neuromuscular blocking agent dose on post-operative respiratory complications (primary endpoint) and secondary endpoints. Confounder-adjusted analyses addressed age, surgical duration, and comorbidity burden. RESULTS: In confounder-adjusted analyses, high doses of neuromuscular blocking agents were associated with higher risk of post-operative respiratory complications (OR 2.27; 95% CI 1.12-4.59; P = .022). The effect was modified by age (P-for-interaction = .016) towards a more substantial risk in infants ≤1 year (OR 3.84; 95% CI 1.35-10.94; P = .012), by duration of surgery (P-for-interaction = .006) towards a higher difference in odds for surgeries <90 minutes (OR 4.25; 95% CI 1.19-15.18; P = .026), and by ASA physical status (P-for-interaction = .015) with a greater effect among patients with higher operative risk (ASA >1: OR 3.17; 95% CI 1.43-7.04; P = .005). Neostigmine reversal did not modify the association between neuromuscular blocking agents and post-operative respiratory complications (P-for-interaction = .38). Instrumental variable analysis confirmed that high doses of neuromuscular blocking agents were associated with post-operative respiratory complications (probit coefficient 0.25; 95% CI 0.04-0.46; P = .022), demonstrating robust results regarding concerns of unobserved confounding. CONCLUSIONS: High dose of neuromuscular blocking agents is associated with post-operative respiratory complications. We have identified subcohorts of paediatric patients who are particularly vulnerable to the respiratory side-effects of neuromuscular blocking agents: infants, paediatric patients undergoing surgeries of short duration, and those with a high ASA risk score.