Two Distinct Modes of Hypoosmotic Medium-Induced Release of Excitatory Amino Acids and Taurine in the Rat Brain In Vivo

A variety of physiological and pathological factors induce cellular swelling in the brain. Changes in cell volume activate several types of ion channels, which mediate the release of inorganic and organic osmolytes and allow for compensatory cell volume decrease. Volume-regulated anion channels (VRAC) are thought to be responsible for the release of some of organic osmolytes, including the excitatory neurotransmitters glutamate and aspartate. In the present study, we compared the in vivo properties of the swelling-activated release of glutamate, aspartate, and another major brain osmolyte taurine. Cell swelling was induced by perfusion of hypoosmotic (low [NaCl]) medium via a microdialysis probe placed in the rat cortex. The hypoosmotic medium produced several-fold increases in the extracellular levels of glutamate, aspartate and taurine. However, the release of the excitatory amino acids differed from the release of taurine in several respects including: (i) kinetic properties, (ii) sensitivity to isoosmotic changes in [NaCl], and (iii) sensitivity to hydrogen peroxide, which is known to modulate VRAC. Consistent with the involvement of VRAC, hypoosmotic medium-induced release of the excitatory amino acids was inhibited by the anion channel blocker DNDS, but not by the glutamate transporter inhibitor TBOA or Cd2+, which inhibits exocytosis. In order to elucidate the mechanisms contributing to taurine release, we studied its release properties in cultured astrocytes and cortical synaptosomes. Similarities between the results obtained in vivo and in synaptosomes suggest that the swelling-activated release of taurine in vivo may be of neuronal origin. Taken together, our findings indicate that different transport mechanisms and/or distinct cellular sources mediate hypoosmotic medium-induced release of the excitatory amino acids and taurine in vivo

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

A Multicenter Observational Study of US Adults with Acute Asthma: Who Are the Frequent Users of the Emergency Department?

Background: Despite the substantial burden of asthma-related emergency department (ED) visits, there have been no recent multicenter efforts to characterize this high-risk population. Objective: We aimed to characterize patients with asthma according to their frequency of ED visits and to identify factors associated with frequent ED visits. Methods: A multicenter chart review study of 48 EDs across 23 US states. We identified ED patients ages 18 to 54 years with acute asthma during 2011 and 2012. Primary outcome was frequency of ED visits for acute asthma in the past year, excluding the index ED visit. Results: Of the 1890 enrolled patients, 863 patients (46%) had 1 or more (frequent) ED visits in the past year. Specifically, 28% had 1 to 2 visits, 11% had 3 to 5 visits, and 7% had 6 or more visits. Among frequent ED users, guideline-recommended management was suboptimal. For example, of patients with 6 or more ED visits, 85% lacked evidence of prior evaluation by an asthma specialist, and 43% were not treated with inhaled corticosteroids. In a multivariable model, significant predictors of frequent ED visits were public insurance, no insurance, and markers for chronic asthma severity (all P &lt; .05). Stronger associations were found among those with a higher frequency of asthma-related ED visits (eg, 6 or more ED visits). Conclusion: This multicenter study of US adults with acute asthma demonstrated many frequent ED users and suboptimal preventive management in this high-risk population. Future reductions in asthma morbidity and associated health care utilization will require continued efforts to bridge these majorgaps in asthma care

A Multicenter Observational Study of US Adults with Acute Asthma: Who Are the Frequent Users of the Emergency Department?

Background: Despite the substantial burden of asthma-related emergency department (ED) visits, there have been no recent multicenter efforts to characterize this high-risk population. Objective: We aimed to characterize patients with asthma according to their frequency of ED visits and to identify factors associated with frequent ED visits. Methods: A multicenter chart review study of 48 EDs across 23 US states. We identified ED patients ages 18 to 54 years with acute asthma during 2011 and 2012. Primary outcome was frequency of ED visits for acute asthma in the past year, excluding the index ED visit. Results: Of the 1890 enrolled patients, 863 patients (46%) had 1 or more (frequent) ED visits in the past year. Specifically, 28% had 1 to 2 visits, 11% had 3 to 5 visits, and 7% had 6 or more visits. Among frequent ED users, guideline-recommended management was suboptimal. For example, of patients with 6 or more ED visits, 85% lacked evidence of prior evaluation by an asthma specialist, and 43% were not treated with inhaled corticosteroids. In a multivariable model, significant predictors of frequent ED visits were public insurance, no insurance, and markers for chronic asthma severity (all P &lt; .05). Stronger associations were found among those with a higher frequency of asthma-related ED visits (eg, 6 or more ED visits). Conclusion: This multicenter study of US adults with acute asthma demonstrated many frequent ED users and suboptimal preventive management in this high-risk population. Future reductions in asthma morbidity and associated health care utilization will require continued efforts to bridge these majorgaps in asthma care