Alzheimer's disease-associated P460L variant of EphA1 dysregulates receptor activity and blood-brain barrier function.

INTRODUCTION: Genome-wide association studies link susceptibility to late-onset Alzheimer's disease (LOAD) with EphA1. Sequencing identified a non-synonymous substitution P460L as a LOAD risk variant. Other Ephs regulate vascular permeability and immune cell recruitment. We hypothesized that P460L dysregulates EphA1 receptor activity and impacts neuroinflammation. METHODS: EphA1/P460L receptor activity was assayed in isogenic Human Embryonic Kidney (HEK) cells. Soluble EphA1/P460L (sEphA1/sP460L) reverse signaling in brain endothelial cells was assessed by T-cell recruitment and barrier function assays. RESULTS: EphA1 and P460L were expressed in HEK cells, but membrane and soluble P460L were significantly reduced. Ligand engagement induced Y781 phosphorylation of EphA1 but not P460L. sEphA1 primed brain endothelial cells for increased T-cell recruitment; however, sP460L was less effective. sEphA1 decreased the integrity of the brain endothelial barrier, while sP460L had no effect. DISCUSSION: These findings suggest that P460L alters EphA1-dependent forward and reverse signaling, which may impact blood-brain barrier function in LOAD. HIGHLIGHTS: EphA1-dependent reverse signaling controls recruitment of T cells by brain endothelial cells. EphA1-dependent reverse signaling remodels brain endothelial cell contacts. LOAD-associated P460L variant of EphA1 shows reduced membrane expression and reduced ligand responses. LOAD-associated P460L variant of EphA1 fails to reverse signal to brain endothelial cells.

Amoxicillin duration and dose for community-acquired pneumonia in children: the CAP-IT factorial non-inferiority RCT.

BACKGROUND: Data are limited regarding the optimal dose and duration of amoxicillin treatment for community-acquired pneumonia in children. OBJECTIVES: To determine the efficacy, safety and impact on antimicrobial resistance of shorter (3-day) and longer (7-day) treatment with amoxicillin at both a lower and a higher dose at hospital discharge in children with uncomplicated community-acquired pneumonia. DESIGN: A multicentre randomised double-blind 2 × 2 factorial non-inferiority trial in secondary care in the UK and Ireland. SETTING: Paediatric emergency departments, paediatric assessment/observation units and inpatient wards. PARTICIPANTS: Children aged > 6 months, weighing 6-24 kg, with a clinical diagnosis of community-acquired pneumonia, in whom treatment with amoxicillin as the sole antibiotic was planned on discharge. INTERVENTIONS: Oral amoxicillin syrup at a dose of 35-50 mg/kg/day compared with a dose of 70-90 mg/kg/day, and 3 compared with 7 days' duration. Children were randomised simultaneously to each of the two factorial arms in a 1 : 1 ratio. MAIN OUTCOME MEASURES: The primary outcome was clinically indicated systemic antibacterial treatment prescribed for respiratory tract infection (including community-acquired pneumonia), other than trial medication, up to 28 days after randomisation. Secondary outcomes included severity and duration of parent/guardian-reported community-acquired pneumonia symptoms, drug-related adverse events (including thrush, skin rashes and diarrhoea), antimicrobial resistance and adherence to trial medication. RESULTS: A total of 824 children were recruited from 29 hospitals. Ten participants received no trial medication and were excluded. Participants [median age 2.5 (interquartile range 1.6-2.7) years; 52% male] were randomised to either 3 (n = 413) or 7 days (n = 401) of trial medication at either lower (n = 410) or higher (n = 404) doses. There were 51 (12.5%) and 49 (12.5%) primary end points in the 3- and 7-day arms, respectively (difference 0.1%, 90% confidence interval -3.8% to 3.9%) and 51 (12.6%) and 49 (12.4%) primary end points in the low- and high-dose arms, respectively (difference 0.2%, 90% confidence interval -3.7% to 4.0%), both demonstrating non-inferiority. Resolution of cough was faster in the 7-day arm than in the 3-day arm for cough (10 days vs. 12 days) (p = 0.040), with no difference in time to resolution of other symptoms. The type and frequency of adverse events and rate of colonisation by penicillin-non-susceptible pneumococci were comparable between arms. LIMITATIONS: End-of-treatment swabs were not taken, and 28-day swabs were collected in only 53% of children. We focused on phenotypic penicillin resistance testing in pneumococci in the nasopharynx, which does not describe the global impact on the microflora. Although 21% of children did not attend the final 28-day visit, we obtained data from general practitioners for the primary end point on all but 3% of children. CONCLUSIONS: Antibiotic retreatment, adverse events and nasopharyngeal colonisation by penicillin-non-susceptible pneumococci were similar with the higher and lower amoxicillin doses and the 3- and 7-day treatments. Time to resolution of cough and sleep disturbance was slightly longer in children taking 3 days' amoxicillin, but time to resolution of all other symptoms was similar in both arms. FUTURE WORK: Antimicrobial resistance genotypic studies are ongoing, including whole-genome sequencing and shotgun metagenomics, to fully characterise the effect of amoxicillin dose and duration on antimicrobial resistance. The analysis of a randomised substudy comparing parental electronic and paper diary entry is also ongoing. TRIAL REGISTRATION: Current Controlled Trials ISRCTN76888927, EudraCT 2016-000809-36 and CTA 00316/0246/001-0006. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 60. See the NIHR Journals Library website for further project information.

Pneumonia (an acute lung infection) is a common diagnosis in young children worldwide. To cure this, some children are given antibiotics, but we do not currently know the best amount (dose) to give and the ideal number of days (duration) of treatment. Taking antibiotics causes changes in bacteria, making them more resistant to treatment. This may be affected by the dose and duration, and is important because resistant bacteria are harder to treat and could spread to other people. Amoxicillin is the most common antibiotic treatment for children with pneumonia. CAP-IT (Community-Acquired Pneumonia: a protocol for a randomIsed controlled Trial) tested if lower doses and shorter durations of amoxicillin are as good as higher doses and longer durations, and whether or not these affect the presence of resistant bacteria. In total, 824 children in the UK and Ireland with pneumonia participated. They received either high- or low-dose amoxicillin for 3 or 7 days following discharge from hospital. To ensure that neither doctors nor parents were influenced by knowing which group a child was in, we included dummy drugs (placebo). We measured how often children were given more antibiotics for respiratory infections in the 4 weeks after starting the trial medicine. To check for resistant bacteria, a nose swab was collected before starting treatment and again after 4 weeks. One in every eight participating children was given additional antibiotics. We found no important difference in this proportion between 3 days and 7 days of amoxicillin treatment, or between lower or higher doses. Although children's coughs took slightly longer to go away when they received only 3 days of antibiotics, rash was reported slightly more often in children taking 7 days of antibiotics. There was no effect of dose of amoxicillin on any of the symptom measurements. No effect of duration of treatment or dose was observed for antibiotic resistance in bacteria living in the nose and throat.

Endothelial cell damage in heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia type II is a severe complication of heparin treatment that may result in thrombosis. When thrombosis occurs it carries a 50% mortality rate. The exact pathophysiology is not fully understood but in the majority of cases it is associated with the production of heparin/platelet factor 4 antibodies. The endothelium provides a protective anticoagulant surface over which blood flows. Perturbation of the endothelial cells causes a reversal of the anticoagulant properties of the cells to that of a procoagulant surface. This is often due to release or down-regulation of the anticoagulant membrane proteins such as thrombomodulin and up-regulation of procoagulant factors such as tissue factor. We studied 10 patients in our cardiothoracic institute with clinically and laboratory-confirmed heparin-induced thrombocytopenia type II for evidence of endothelial cell damage. There was a statistically significant rise in the concentrations of von Willebrand factor (P < 0.0001) and soluble thrombomodulin (P = 0.004) when patients with heparin-induced thrombocytopenia type II were compared with healthy laboratory controls and patients having had cardiopulmonary bypass surgery (von Willebrand factor 324 versus 103 versus 108 U/dl and soluble thrombomodulin 9.5 versus 2.3 versus 1.2 ng/ml, respectively). Our findings suggest that endothelial cell damage is a major factor in the pathophysiology of heparin-induced thrombocytopenia.

A re-appraisal of the reliability of the 20 m multi-stage shuttle run test.

Most studies that have set out to quantify the test-retest reliability of the multi-stage shuttle run test (MSSRT) have typically used inappropriate statistics (correlation coefficients) and/or one of two possible calculation methods for deriving predictions of maximal oxygen uptake (VO2max), and have not considered the impact of habituation on performance in the MSSRT and whether its reliability improves beyond a single repeat trial. In this context, the aim of this study was to assess the reliability of the MSSRT over three trials. Thirty-five healthy and active university games players (22 males and 13 females) performed the MSSRT on three occasions, 1 week apart. Individual total numbers of completed shuttles were recorded and estimated VO2max values were derived via established equation and table methods. Analysis revealed that the overall mean VO2max score from the equation method (52.5 +/- 7.8 ml kg(-1) min(-1)) was significantly higher than that for the table (46.9 +/- 8.9 ml kg(-1) min(-1)), whilst the mean trial 2 and trial 3 scores were significantly higher than that for trial 1, but not different to each other. The Limits of Agreement for the table method were -1.4 +/- 5.0 (trial 1-trial 2) and 0.0 +/- 5.5 ml kg(-1) min(-1) (trial 2-trial 3), and for the equation method -1.1 +/- 4.7 (trial 1-trial 2) and 0.0 +/- 5.0 ml kg(-1) min(-1) (trial 2-trial 3). These results suggest that systematic bias is eliminated after the first trial (due to habituation), but a considerable amount of random error remains, regardless of the type of score calculated. Hence, among our sample, the MSSRT does not appear to be reliable enough for the purpose of monitoring changes in VO2max due to non-random reasons.