Activation of the GLP-1 receptor by a non-peptidic agonist.

Class B G-protein-coupled receptors are major targets for the treatment of chronic diseases, including diabetes and obesity1. Structures of active receptors reveal peptide agonists engage deep within the receptor core, leading to an outward movement of extracellular loop 3 and the tops of transmembrane helices 6 and 7, an inward movement of transmembrane helix 1, reorganization of extracellular loop 2 and outward movement of the intracellular side of transmembrane helix 6, resulting in G-protein interaction and activation2-6. Here we solved the structure of a non-peptide agonist, TT-OAD2, bound to the glucagon-like peptide-1 (GLP-1) receptor. Our structure identified an unpredicted non-peptide agonist-binding pocket in which reorganization of extracellular loop 3 and transmembrane helices 6 and 7 manifests independently of direct ligand interaction within the deep transmembrane domain pocket. TT-OAD2 exhibits biased agonism, and kinetics of G-protein activation and signalling that are distinct from peptide agonists. Within the structure, TT-OAD2 protrudes beyond the receptor core to interact with the lipid or detergent, providing an explanation for the distinct activation kinetics that may contribute to the clinical efficacy of this compound series. This work alters our understanding of the events that drive the activation of class B receptors.

Threespine Stickleback: A Model System For Evolutionary Genomics.

The repeated adaptation of oceanic threespine sticklebacks to fresh water has made it a premier organism to study parallel evolution. These small fish have multiple distinct ecotypes that display a wide range of diverse phenotypic traits. Ecotypes are easily crossed in the laboratory, and families are large and develop quickly enough for quantitative trait locus analyses, positioning the threespine stickleback as a versatile model organism to address a wide range of biological questions. Extensive genomic resources, including linkage maps, a high-quality reference genome, and developmental genetics tools have led to insights into the genomic basis of adaptation and the identification of genomic changes controlling traits in vertebrates. Recently, threespine sticklebacks have been used as a model system to identify the genomic basis of highly complex traits, such as behavior and host-microbiome and host-parasite interactions. We review the latest findings and new avenues of research that have led the threespine stickleback to be considered a supermodel of evolutionary genomics.

Inferring the evolution of reproductive isolation in a lineage of fossil threespine stickleback, Gasterosteus doryssus.

Darwin attributed the absence of species transitions in the fossil record to his hypothesis that speciation occurs within isolated habitat patches too geographically restricted to be captured by fossil sequences. Mayr's peripatric speciation model added that such speciation would be rapid, further explaining missing evidence of diversification. Indeed, Eldredge and Gould's original punctuated equilibrium model combined Darwin's conjecture, Mayr's model and 124 years of unsuccessfully sampling the fossil record for transitions. Observing such divergence, however, could illustrate the tempo and mode of evolution during early speciation. Here, we investigate peripatric divergence in a Miocene stickleback fish, Gasterosteus doryssus. This lineage appeared and, over approximately 8000 generations, evolved significant reduction of 12 of 16 traits related to armour, swimming and diet, relative to its ancestral population. This was greater morphological divergence than we observed between reproductively isolated, benthic-limnetic ecotypes of extant Gasterosteus aculeatus. Therefore, we infer that reproductive isolation was evolving. However, local extinction of G. doryssus lineages shows how young, isolated, speciating populations often disappear, supporting Darwin's explanation for missing evidence and revealing a mechanism behind morphological stasis. Extinction may also account for limited sustained divergence within the stickleback species complex and help reconcile speciation rate variation observed across time scales.

Early bolus epinephrine administration during pediatric cardiopulmonary resuscitation for bradycardia with poor perfusion: an ICU-resuscitation study.

BACKGROUND: Half of pediatric in-hospital cardiopulmonary resuscitation (CPR) events have an initial rhythm of non-pulseless bradycardia with poor perfusion. Our study objectives were to leverage granular data from the ICU-RESUScitation (ICU-RESUS) trial to: (1) determine the association of early epinephrine administration with survival outcomes in children receiving CPR for bradycardia with poor perfusion; and (2) describe the incidence and time course of the development of pulselessness. METHODS: Prespecified secondary analysis of ICU-RESUS, a multicenter cluster randomized trial of children (< 19 years) receiving CPR in 18 intensive care units in the United States. Index events (October 2016-March 2021) lasting ≥ 2 min with a documented initial rhythm of bradycardia with poor perfusion were included. Associations between early epinephrine (first 2 min of CPR) and outcomes were evaluated with Poisson multivariable regression controlling for a priori pre-arrest characteristics. Among patients with arterial lines, intra-arrest blood pressure waveforms were reviewed to determine presence of a pulse during CPR interruptions. The temporal nature of progression to pulselessness was described and outcomes were compared between patients according to subsequent pulselessness status. RESULTS: Of 452 eligible subjects, 322 (71%) received early epinephrine. The early epinephrine group had higher pre-arrest severity of illness and vasoactive-inotrope scores. Early epinephrine was not associated with survival to discharge (aRR 0.97, 95%CI 0.82, 1.14) or survival with favorable neurologic outcome (aRR 0.99, 95%CI 0.82, 1.18). Among 186 patients with invasive blood pressure waveforms, 118 (63%) had at least 1 period of pulselessness during the first 10 min of CPR; 86 (46%) by 2 min and 100 (54%) by 3 min. Sustained return of spontaneous circulation was highest after bradycardia with poor perfusion (84%) compared to bradycardia with poor perfusion progressing to pulselessness (43%) and bradycardia with poor perfusion progressing to pulselessness followed by return to bradycardia with poor perfusion (62%) (p < 0.001). CONCLUSIONS: In this cohort of pediatric CPR events with an initial rhythm of bradycardia with poor perfusion, we failed to identify an association between early bolus epinephrine and outcomes when controlling for illness severity. Most children receiving CPR for bradycardia with poor perfusion developed subsequent pulselessness, 46% within 2 min of CPR onset.

Brief report: incidence and outcomes of pediatric tracheal intubation-associated cardiac arrests in the ICU-RESUS clinical trial.

BACKGROUND: Tracheal intubation (TI)-associated cardiac arrest (TI-CA) occurs in 1.7% of pediatric ICU TIs. Our objective was to evaluate resuscitation characteristics and outcomes between cardiac arrest patients with and without TI-CA. METHODS: Secondary analysis of cardiac arrest patients in both ICU-RESUS trial and ancillary CPR-NOVA study. The primary exposure was TI-CA, defined as cardiac arrest occurred during TI procedure or within 20 min after endotracheal tube placement. The primary outcome was survival to hospital discharge with favorable neurological outcome (Pediatric Cerebral Performance Category score 1-3 or unchanged). RESULTS: Among 315 children with cardiac arrests, 48 (15.2%) met criteria for TI-CA. Pre-existing medical conditions were similar between groups. Pre-arrest non-invasive mechanical ventilation was more common among TI-CA patients (18/48, 37.5%) compared to non-TI-CA patients (35/267, 13.1%). In 48% (23/48), the TI-CA occurred within 20 min after intubation (i.e., not during intubation). Duration of CPR was longer in TI-CA patients (median 11.0 min, interquartile range [IQR]: 2.5, 35.5) than non-TI-CA patients (median 5.0 min, IQR 2.0, 21.0), p = 0.03. Return of spontaneous circulation occurred in 32/48 (66.7%) TI-CA versus 186/267 (69.7%) non-TI-CA, p = 0.73. Survival to hospital discharge with favorable neurological outcome occurred in 29/48 (60.4%) TI-CA versus 146/267 (54.7%) non-TI-CA, p = 0.53. CONCLUSIONS: Fifteen percent of these pediatric ICU cardiac arrests were associated with TI. Half of TI-CA occurred after endotracheal tube placement. While duration of CPR was longer in TI-CA patients, there were no differences in unadjusted outcomes following TI-CA versus non-TI-CA. TRIAL REGISTRATION: The ICU-RESUS (ClinicalTrials.gov Identifier: NCT02837497).

Survival With Favorable Neurologic Outcome and Quality of Cardiopulmonary Resuscitation Following In-Hospital Cardiac Arrest in Children With Cardiac Disease Compared With Noncardiac Disease.

OBJECTIVES: To assess associations between outcome and cardiopulmonary resuscitation (CPR) quality for in-hospital cardiac arrest (IHCA) in children with medical cardiac, surgical cardiac, or noncardiac disease. DESIGN: Secondary analysis of a multicenter cluster randomized trial, the ICU-RESUScitation Project (NCT02837497, 2016-2021). SETTING: Eighteen PICUs. PATIENTS: Children less than or equal to 18 years old and greater than or equal to 37 weeks postconceptual age receiving chest compressions (CC) of any duration during the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 1,100 children with IHCA, there were 273 medical cardiac (25%), 383 surgical cardiac (35%), and 444 noncardiac (40%) cases. Favorable neurologic outcome was defined as no more than moderate disability or no worsening from baseline Pediatric Cerebral Performance Category at discharge. The medical cardiac group had lower odds of survival with favorable neurologic outcomes compared with the noncardiac group (48% vs 55%; adjusted odds ratio [aOR] [95% CI], aOR 0.59 [95% CI, 0.39-0.87], p = 0.008) and surgical cardiac group (48% vs 58%; aOR 0.64 [95% CI, 0.45-0.9], p = 0.01). We failed to identify a difference in favorable outcomes between surgical cardiac and noncardiac groups. We also failed to identify differences in CC rate, CC fraction, ventilation rate, intra-arrest average target diastolic or systolic blood pressure between medical cardiac versus noncardiac, and surgical cardiac versus noncardiac groups. The surgical cardiac group had lower odds of achieving target CC depth compared to the noncardiac group (OR 0.15 [95% CI, 0.02-0.52], p = 0.001). We failed to identify a difference in the percentage of patients achieving target CC depth when comparing medical cardiac versus noncardiac groups. CONCLUSIONS: In pediatric IHCA, medical cardiac patients had lower odds of survival with favorable neurologic outcomes compared with noncardiac and surgical cardiac patients. We failed to find differences in CPR quality between medical cardiac and noncardiac patients, but there were lower odds of achieving target CC depth in surgical cardiac compared to noncardiac patients.

Early Cardiac Arrest Hemodynamics, End-Tidal C o2 , and Outcome in Pediatric Extracorporeal Cardiopulmonary Resuscitation: Secondary Analysis of the ICU-RESUScitation Project Dataset (2016-2021).

OBJECTIVES: Cannulation for extracorporeal membrane oxygenation during active extracorporeal cardiopulmonary resuscitation (ECPR) is a method to rescue patients refractory to standard resuscitation. We hypothesized that early arrest hemodynamics and end-tidal C o2 (ET co2 ) are associated with survival to hospital discharge with favorable neurologic outcome in pediatric ECPR patients. DESIGN: Preplanned, secondary analysis of pediatric Utstein, hemodynamic, and ventilatory data in ECPR patients collected during the 2016-2021 Improving Outcomes from Pediatric Cardiac Arrest study; the ICU-RESUScitation Project (ICU-RESUS; NCT02837497). SETTING: Eighteen ICUs participated in ICU-RESUS. PATIENTS: There were 97 ECPR patients with hemodynamic waveforms during cardiopulmonary resuscitation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Overall, 71 of 97 patients (73%) were younger than 1 year old, 82 of 97 (85%) had congenital heart disease, and 62 of 97 (64%) were postoperative cardiac surgical patients. Forty of 97 patients (41%) survived with favorable neurologic outcome. We failed to find differences in diastolic or systolic blood pressure, proportion achieving age-based target diastolic or systolic blood pressure, or chest compression rate during the initial 10 minutes of CPR between patients who survived with favorable neurologic outcome and those who did not. Thirty-five patients had ET co2 data; of 17 survivors with favorable neurologic outcome, four of 17 (24%) had an average ET co2 less than 10 mm Hg and two (12%) had a maximum ET co2 less than 10 mm Hg during the initial 10 minutes of resuscitation. CONCLUSIONS: We did not identify an association between early hemodynamics achieved by high-quality CPR and survival to hospital discharge with favorable neurologic outcome after pediatric ECPR. Candidates for ECPR with ET co2 less than 10 mm Hg may survive with favorable neurologic outcome.

Social Environment and Neurobehavioral Outcomes 1 Year After Severe Pediatric TBI in the Intensive Care Unit.

OBJECTIVE: To examine the association of home and neighborhood environment with neurobehavioral outcomes after severe pediatric traumatic brain injury (TBI). SETTING: Domestic and international children's medical centers. PARTICIPANTS: Participants enrolled in the study were 18 years or younger at the time of their severe TBI (Glasgow Coma Scale [GCS] ≤ 8), admitted to the intensive care unit, and underwent placement of an intracranial pressure (ICP) monitor. Exclusionary criteria included less severe injury (GCS > 8), pregnancy, and/or ICP monitor placement occurred at a non-participating hospital. DESIGN: A multicenter, observational cohort study. MAIN MEASURES: Outcomes assessed at 12 months post-injury included measures of global functioning, intellectual ability, caregiver-report measures of family functioning, executive functioning behaviors, behavior problems, and health-related quality of life. We examined mortality risk (assessed acutely after injury), family functioning (assessed at 12 months post-injury) and parenting practices, social environment, and neighborhood stressors (all assessed > 12 months post-injury), as correlates and moderators of the 12-month post-injury outcomes. RESULTS: Home and neighborhood factors were associated with neurobehavioral outcomes (ie, intellectual ability, executive functioning, behavioral adjustment, and health-related quality of life) but not with global functioning outcomes. A negative association between a more vulnerable home and neighborhood environment and neurobehavioral outcomes was more consistent in older children compared with younger children, based on age of injury. The influence of mortality risk on neurobehavioral outcomes was variable. CONCLUSION: Parenting practices and quality of social and neighborhood environment are associated with neurobehavioral outcomes 12 months after severe pediatric TBI. More research is needed to better understand the relationship between home/neighborhood stressors and TBI recovery to develop and implement strategies for patients and families to optimize outcomes. Future intervention development should focus on addressing parenting practices and social environment in a developmentally sensitive way for children who have sustained a severe TBI.

Longer or shorter spines: Reciprocal trait evolution in stickleback via triallelic regulatory changes in Stanniocalcin2a.

Vertebrates have repeatedly modified skeletal structures to adapt to their environments. The threespine stickleback is an excellent system for studying skeletal modifications, as different wild populations have either increased or decreased the lengths of their prominent dorsal and pelvic spines in different freshwater environments. Here we identify a regulatory locus that has a major morphological effect on the length of stickleback dorsal and pelvic spines, which we term Maser (major spine enhancer). Maser maps in a closely linked supergene complex that controls multiple armor, feeding, and behavioral traits on chromosome IV. Natural alleles in Maser are differentiated between marine and freshwater sticklebacks; however, alleles found among freshwater populations are also differentiated, with distinct alleles found in short- and long-spined freshwater populations. The distinct freshwater alleles either increase or decrease expression of the bone growth inhibitor gene Stanniocalcin2a in developing spines, providing a simple genetic mechanism for either increasing or decreasing spine lengths in natural populations. Genomic surveys suggest many recurrently differentiated loci in sticklebacks are similarly specialized into three or more distinct alleles, providing multiple ancient standing variants in particular genes that may contribute to a range of phenotypes in different environments.

Fitness maps to a large-effect locus in introduced stickleback populations.

Mutations of small effect underlie most adaptation to new environments, but beneficial variants with large fitness effects are expected to contribute under certain conditions. Genes and genomic regions having large effects on phenotypic differences between populations are known from numerous taxa, but fitness effect sizes have rarely been estimated. We mapped fitness over a generation in an F2 intercross between a marine and a lake stickleback population introduced to a freshwater pond. A quantitative trait locus map of the number of surviving offspring per F2 female detected a single, large-effect locus near Ectodysplasin (Eda), a gene having an ancient freshwater allele causing reduced bony armor and other changes. F2 females homozygous for the freshwater allele had twice the number of surviving offspring as homozygotes for the marine allele, producing a large selection coefficient, s = 0.50 ± 0.09 SE. Correspondingly, the frequency of the freshwater allele increased from 0.50 in F2 mothers to 0.58 in surviving offspring. We compare these results to allele frequency changes at the Eda gene in an Alaskan lake population colonized by marine stickleback in the 1980s. The frequency of the freshwater Eda allele rose steadily over multiple generations and reached 95% within 20 y, yielding a similar estimate of selection, s = 0.49 ± 0.05, but a different degree of dominance. These findings are consistent with other studies suggesting strong selection on this gene (and/or linked genes) in fresh water. Selection on ancient genetic variants carried by colonizing ancestors is likely to increase the prevalence of large-effect fitness variants in adaptive evolution.

Diastolic Blood Pressure Threshold During Pediatric Cardiopulmonary Resuscitation and Survival Outcomes: A Multicenter Validation Study.

OBJECTIVES: Arterial diastolic blood pressure (DBP) greater than 25 mm Hg in infants and greater than 30 mm Hg in children greater than 1 year old during cardiopulmonary resuscitation (CPR) was associated with survival to hospital discharge in one prospective study. We sought to validate these potential hemodynamic targets in a larger multicenter cohort. DESIGN: Prospective observational study. SETTING: Eighteen PICUs in the ICU-RESUScitation prospective trial from October 2016 to March 2020. PATIENTS: Children less than or equal to 18 years old with CPR greater than 30 seconds and invasive blood pressure (BP) monitoring during CPR. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Invasive BP waveform data and Utstein-style CPR data were collected, including prearrest patient characteristics, intra-arrest interventions, and outcomes. Primary outcome was survival to hospital discharge, and secondary outcomes were return of spontaneous circulation (ROSC) and survival to hospital discharge with favorable neurologic outcome. Multivariable Poisson regression models with robust error estimates evaluated the association of DBP greater than 25 mm Hg in infants and greater than 30 mm Hg in older children with these outcomes. Among 1,129 children with inhospital cardiac arrests, 413 had evaluable DBP data. Overall, 85.5% of the patients attained thresholds of mean DBP greater than or equal to 25 mm Hg in infants and greater than or equal to 30 mm Hg in older children. Initial return of circulation occurred in 91.5% and 25% by placement on extracorporeal membrane oxygenator. Survival to hospital discharge occurred in 58.6%, and survival with favorable neurologic outcome in 55.4% (i.e. 94.6% of survivors had favorable neurologic outcomes). Mean DBP greater than 25 mm Hg for infants and greater than 30 mm Hg for older children was significantly associated with survival to discharge (adjusted relative risk [aRR], 1.32; 1.01-1.74; p = 0.03) and ROSC (aRR, 1.49; 1.12-1.97; p = 0.002) but did not reach significance for survival to hospital discharge with favorable neurologic outcome (aRR, 1.30; 0.98-1.72; p = 0.051). CONCLUSIONS: These validation data demonstrate that achieving mean DBP during CPR greater than 25 mm Hg for infants and greater than 30 mm Hg for older children is associated with higher rates of survival to hospital discharge, providing potential targets for DBP during CPR.

Genetically encoded multivalent liquid glycan array displayed on M13 bacteriophage.

The central dogma of biology does not allow for the study of glycans using DNA sequencing. We report a liquid glycan array (LiGA) platform comprising a library of DNA 'barcoded' M13 virions that display 30-1,500 copies of glycans per phage. A LiGA is synthesized by acylation of the phage pVIII protein with a dibenzocyclooctyne, followed by ligation of azido-modified glycans. Pulldown of the LiGA with lectins followed by deep sequencing of the barcodes in the bound phage decodes the optimal structure and density of the recognized glycans. The LiGA is target agnostic and can measure the glycan-binding profile of lectins, such as CD22, on cells in vitro and immune cells in a live mouse. From a mixture of multivalent glycan probes, LiGAs identify the glycoconjugates with optimal avidity necessary for binding to lectins on living cells in vitro and in vivo.

Identification of post-cardiac arrest blood pressure thresholds associated with outcomes in children: an ICU-Resuscitation study.

INTRODUCTION: Though early hypotension after pediatric in-hospital cardiac arrest (IHCA) is associated with inferior outcomes, ideal post-arrest blood pressure (BP) targets have not been established. We aimed to leverage prospectively collected BP data to explore the association of post-arrest BP thresholds with outcomes. We hypothesized that post-arrest systolic and diastolic BP thresholds would be higher than the currently recommended post-cardiopulmonary resuscitation BP targets and would be associated with higher rates of survival to hospital discharge. METHODS: We performed a secondary analysis of prospectively collected BP data from the first 24 h following return of circulation from index IHCA events enrolled in the ICU-RESUScitation trial (NCT02837497). The lowest documented systolic BP (SBP) and diastolic BP (DBP) were percentile-adjusted for age, height and sex. Receiver operator characteristic curves and cubic spline analyses controlling for illness category and presence of pre-arrest hypotension were generated exploring the association of lowest post-arrest SBP and DBP with survival to hospital discharge and survival to hospital discharge with favorable neurologic outcome (Pediatric Cerebral Performance Category of 1-3 or no change from baseline). Optimal cutoffs for post-arrest BP thresholds were based on analysis of receiver operator characteristic curves and spline curves. Logistic regression models accounting for illness category and pre-arrest hypotension examined the associations of these thresholds with outcomes. RESULTS: Among 693 index events with 0-6 h post-arrest BP data, identified thresholds were: SBP > 10th percentile and DBP > 50th percentile for age, sex and height. Fifty-one percent (n = 352) of subjects had lowest SBP above threshold and 50% (n = 346) had lowest DBP above threshold. SBP and DBP above thresholds were each associated with survival to hospital discharge (SBP: aRR 1.21 [95% CI 1.10, 1.33]; DBP: aRR 1.23 [1.12, 1.34]) and survival to hospital discharge with favorable neurologic outcome (SBP: aRR 1.22 [1.10, 1.35]; DBP: aRR 1.27 [1.15, 1.40]) (all p < 0.001). CONCLUSIONS: Following pediatric IHCA, subjects had higher rates of survival to hospital discharge and survival to hospital discharge with favorable neurologic outcome when BP targets above a threshold of SBP > 10th percentile for age and DBP > 50th percentile for age during the first 6 h post-arrest.

Neuromonitoring During ECMO Support in Children.

Extracorporeal membrane oxygenation is a potentially lifesaving intervention for children with severe cardiac or respiratory failure. It is used with increasing frequency and in increasingly more complex and severe diseases. Neurological injuries are important causes of morbidity and mortality in children treated with extracorporeal membrane oxygenation and include ischemic stroke, intracranial hemorrhage, hypoxic-ischemic injury, and seizures. In this review, we discuss the epidemiology and pathophysiology of neurological injury in patients supported with extracorporeal membrane oxygenation, and we review the current state of knowledge for available modalities of monitoring neurological function in these children. These include structural imaging with computed tomography and ultrasound, cerebral blood flow monitoring with near-infrared spectroscopy and transcranial Doppler ultrasound, and physiological monitoring with electroencephalography and plasma biomarkers. We highlight areas of need and emerging advances that will improve our understanding of neurological injury related to extracorporeal membrane oxygenation and help to reduce the burden of neurological sequelae in these children.

Temporal Patterns in Brain Tissue and Systemic Oxygenation Associated with Mortality After Severe Traumatic Brain Injury in Children.

BACKGROUND: Brain tissue hypoxia is an independent risk factor for unfavorable outcomes in traumatic brain injury (TBI); however, systemic hyperoxemia encountered in the prevention and/or response to brain tissue hypoxia may also impact risk of mortality. We aimed to identify temporal patterns of partial pressure of oxygen in brain tissue (PbtO2), partial pressure of arterial oxygen (PaO2), and PbtO2/PaO2 ratio associated with mortality in children with severe TBI. METHODS: Data were extracted from the electronic medical record of a quaternary care children's hospital with a level I trauma center for patients ≤ 18 years old with severe TBI and the presence of PbtO2 and/or intracranial pressure monitors. Temporal analyses were performed for the first 5 days of hospitalization by using locally estimated scatterplot smoothing for less than 1,000 observations and generalized additive models with integrated smoothness estimation for more than 1,000 observations. RESULTS: A total of 138 intracranial pressure-monitored patients with TBI (median 5.0 [1.9-12.8] years; 65% boys; admission Glasgow Coma Scale score 4 [3-7]; mortality 18%), 71 with PbtO2 monitors and 67 without PbtO2 monitors were included. Distinct patterns in PbtO2, PaO2, and PbtO2/PaO2 were evident between survivors and nonsurvivors over the first 5 days of hospitalization. Time-series analyses showed lower PbtO2 values on day 1 and days 3-5 and lower PbtO2/PaO2 ratios on days 1, 2, and 5 among patients who died. Analysis of receiver operating characteristics curves using Youden's index identified a PbtO2 of 30 mm Hg and a PbtO2/PaO2 ratio of 0.12 as the cut points for discriminating between survivors and nonsurvivors. Univariate logistic regression identified PbtO2 < 30 mm Hg, hyperoxemia (PaO2 ≥ 300 mm Hg), and PbtO2/PaO2 ratio < 0.12 to be independently associated with mortality. CONCLUSIONS: Lower PbtO2, higher PaO2, and lower PbtO2/PaO2 ratio, consistent with impaired oxygen diffusion into brain tissue, were associated with mortality in this cohort of children with severe TBI. These results corroborate our prior work that suggests targeting a higher PbtO2 threshold than recommended in current guidelines and highlight the potential use of the PbtO2/PaO2 ratio in the management of severe pediatric TBI.

Anticoagulation practices associated with bleeding and thrombosis in pediatric extracorporeal membrane oxygenation; a multi-center secondary analysis.

To determine associations between anticoagulation practices and bleeding and thrombosis during pediatric extracorporeal membrane oxygenation (ECMO), we performed a secondary analysis of prospectively collected data which included 481 children (<19 years), between January 2012 and September 2014. The primary outcome was bleeding or thrombotic events. Bleeding events included a blood product transfusion >80 ml/kg on any day, pulmonary hemorrhage, or intracranial bleeding, Thrombotic events included pulmonary emboli, intracranial clot, limb ischemia, cardiac clot, and arterial cannula or entire circuit change. Bleeding occurred in 42% of patients. Five percent of subjects thrombosed, of which 89% also bled. Daily bleeding odds were independently associated with day prior activated clotting time (ACT) (OR 1.03, 95% CI= 1.00, 1.05, p=0.047) and fibrinogen levels (OR 0.90, 95% CI 0.84, 0.96, p <0.001). Thrombosis odds decreased with increased day prior heparin dose (OR 0.88, 95% CI 0.81, 0.97, p=0.006). Lower ACT values and increased fibrinogen levels may be considered to decrease the odds of bleeding. Use of this single measure, however, may not be sufficient alone to guide optimal anticoagulation practice during ECMO.

Mahalanobis distance tractometry (MaD-Tract) - a framework for personalized white matter anomaly detection applied to TBI.

Imaging-based quantitative measures from diffusion-weighted MRI (dMRI) offer the ability to non-invasively extract microscopic information from human brain tissues. Group-level comparisons of such measures represent an important approach to investigate abnormal brain conditions. These types of analyses are especially useful when the regions of abnormality spatially coincide across subjects. When this is not true, approaches for individualized analyses are necessary. Here we present a framework for single-subject multidimensional analysis based on the Mahalanobis distance. This is conducted along specific white matter pathways represented by tractography-derived streamline bundles. A definition for abnormality was constructed from Wilk's criterion, which accounts for normative sample size, number of features used in the Mahalanobis distance, and multiple comparisons. One example of a condition exhibiting high heterogeneity across subjects is traumatic brain injury (TBI). Using the Mahalanobis distance computed from the three eigenvalues of the diffusion tensor along the cingulum, uncinate, and parcellated corpus callosum tractograms, 8 severe TBI patients were individually compared to a normative sample of 49 healthy controls. For all TBI patients, the analyses showed statistically significant deviations from the normative data at one or multiple locations along the analyzed bundles. The detected anomalies were widespread across the analyzed tracts, consistent with the expected heterogeneity that is hallmark of TBI. Each of the controls subjects was also compared to the remaining 48 subjects in the control group in a leave-one-out fashion. Only two segments were identified as abnormal out of the entire analysis in the control group, thus the method also demonstrated good specificity.

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.

Evolution of static allometry and constraint on evolutionary allometry in a fossil stickleback.

Allometric scaling describes the relationship of trait size to body size within and among taxa. The slope of the population-level regression of trait size against body size (i.e. static allometry) is typically invariant among closely related populations and species. Such invariance is commonly interpreted to reflect a combination of developmental and selective constraints that delimit a phenotypic space into which evolution could proceed most easily. Thus, understanding how allometric relationships do eventually evolve is important to understanding phenotypic diversification. In a lineage of fossil Threespine Stickleback (Gasterosteus doryssus), we investigated the evolvability of static allometric slopes for nine traits (five armour and four non-armour) that evolved significant trait differences across 10 samples over 8500 years. The armour traits showed weak static allometric relationships and a mismatch between those slopes and observed evolution. This suggests that observed evolution in these traits was not constrained by relationships with body size, perhaps because prior, repeated adaptation to freshwater habitats by Threespine Stickleback had generated strong selection to break constraint. In contrast, for non-armour traits, we found stronger allometric relationships. Those allometric slopes did evolve on short time scales. However, those changes were small and fluctuating and the slopes remained strong predictors of the evolutionary trajectory of trait means over time (i.e. evolutionary allometry), supporting the hypothesis of allometry as constraint.

One-Pot Regioselective Diacylation of Pyranoside 1,2-cis Diols.

A one-pot strategy for functionalizing pyranoside 1,2-cis-diols with two different ester protecting groups is reported. The approach employs regioselective acylation via orthoester hydrolysis promoted by a carboxylic acid, e.g., levulinic acid, acetic acid, benzoic acid, or chloroacetic acid. Upon removal of water and introduction of a coupling agent, the carboxylic acid is esterified to the hydroxyl group liberated during hydrolysis. Although applied to 1,2-cis-diols on pyranoside scaffolds, the method should be applicable to such motifs on any six-membered ring.