Abstract 109: Platelets Amplify Endotheliopathy In Covid-19

In addition to their pivotal role in thrombosis and hemostasis, platelets participate in inflammatory responses and endothelial cell activation - hallmarks in the pathogenesis of coronavirus disease 2019 (COVID-19). Given the evidence for a hyperactive platelet phenotype in COVID-19, we investigated effector cell properties of COVID-19 platelets on endothelial cells (ECs). To explore this interaction, ECs were treated with platelet releasate from patients with and without COVID-19, and EC mRNA sequencing performed. We demonstrate that platelet released factors in COVID-19 promote an inflammatory hypercoagulable endotheliopathy. Investigation of the COVID-19 platelet transcriptome identified pathways related to organelle/granule release, metabolism, and immune effector function in addition to upregulation of S100A8 and S100A9 mRNA. Incubation of primary megakaryocytes with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also induced upregulation of S100A8 and S100A9 mRNA. Consistent with increased gene expression, the heterodimer protein product of S100A8 / A9 , myeloid-related protein (MRP)8/14, was released to a greater extent by platelets from COVID-19 patients relative to controls. We demonstrate that platelet-derived MRP8/14 activates microvascular endothelial cells, promotes an inflammatory hypercoagulable phenotype, and is a significant contributor to thromboinflammation and poor clinical outcomes in COVID-19 patients. Finally, we present evidence that therapeutic targeting of platelet P2Y 12 represents a promising candidate to reduce proinflammatory and prothrombotic platelet-endothelial interactions. Altogether, these findings demonstrate a previously unappreciated role for platelets and their activation-induced endotheliopathy in COVID-19.

0039 The Clinical Utility of Dim Light Melatonin Onset in Treatment of Delayed Sleep-Wake Phase Disorder: Preliminary Findings

Introduction

Delayed sleep-wake phase disorder (DSWPD) is common, debilitating, and challenging to treat. In an ongoing randomized trial, we are comparing exogenous melatonin treatment outcomes in DSWPD participants for whom dim light melatonin onset (DLMO) is measured objectively vs. estimated.

Methods

Thus far, 13 participants (27±6 years old, 67% female) have completed a randomized, controlled, double-blind 4-week trial of 0.5 mg of exogenous melatonin timed to either 3 h before measured DLMO (M-DLMO, n = 6) or 3 h before DLMO estimated at 2 h before average sleep onset time based on at least 7 days of wrist actigraphy and sleep diary (E-DLMO, n = 7). All participants met International Classification of Sleep Disorders-3 diagnostic criteria for DSWPD and were otherwise healthy. Participants completed 4 weekly treatment sessions with a blinded psychologist; time of melatonin administration and bed-rise schedule were advanced up to 1 h/week. A validated home saliva collection kit measured DLMO in all participants. Between-group t-tests and Hedges’ g effect sizes (ES) were calculated at post-treatment for the following outcomes: DLMO; Pittsburgh Sleep Quality Index (PSQI) global score; Morningness-Eveningness Questionnaire (MEQ); and the actigraphy parameters sleep efficiency (SE) and clock time of sleep onset and offset. A paired-sample t-test compared the measured vs. estimated DLMO at baseline.

Results

The M-DLMO group had a 65±88 mins DLMO advance vs. 27±30 mins in the E-DLMO group (ES=0.51 p=.381). PSQI scores were similar between groups (M-DLMO=6.67±2.06, E-DLMO=7.1± 1.57, ES=-0.24, p=.646), as were MEQ scores (M-DLMO=43±4.98, E-DLMO=48±12.72, ES=-0.47, p=.387). Sleep onset time (M-DLMO=0:32±1:02, E-DLMO=0:31±1:38, ES=0.01, p=.98) and offset time (M-DLMO=8:05±1:03, E-DLMO=8:08±2:14, ES=-0.02, p=.968) were similar between the groups, although sleep was more efficient in M-DLMO vs. E-DLMO (84%±3% vs. 76%±10%, ES=0.94, p=.096). On average, baseline measured DLMO occurred 123±83 mins earlier than estimated DLMO (p=.001).

Conclusion

We are continuing to enroll participants in this trial. Preliminary results suggest some potential benefit of measuring the DLMO, but results will need to be clarified in a larger sample.

Support

American Sleep Medicine Foundation Strategic Research Award

Time to Improve Informed Consent for Dialysis: An International Perspective

The literature reveals that current nephrology practice in obtaining informed consent for dialysis falls short of ethical and legal requirements. Meeting these requirements represents a significant challenge, especially because the benefits and risks of dialysis have shifted significantly with the growing number of older, comorbid patients. The importance of informed consent for dialysis is heightened by several concerns, including: (1) the proportion of predialysis patients and patients on dialysis who lack capacity in decision making and (2) whether older, comorbid, and frail patients understand their poor prognosis and the full implications to their independence and functional status of being on dialysis. This article outlines the ethical and legal requirements for a valid informed consent to dialysis: (1) the patient was competent, (2) the consent was made voluntarily, and (3) the patient was given sufficient information in an understandable manner to make the decision. It then considers the application of these requirements to practice across different countries. In the process of informed consent, the law requires a discussion by the physician of the material risks associated with dialysis and alternative options. We argue that, legally and ethically, this discussion should include both the anticipated trajectory of the illness and the effect on the life of the patient with particular regard to the outcomes most important to the individual. In addition, a discussion should occur about the option of a conservative, nondialysis pathway. These requirements ensure that the ethical principle of respect for patient autonomy is honored in the context of dialysis. Nephrologists need to be open to, comfortable with, and skillful in communicating this information. From these clear, open, ethically, and legally valid consent discussions, a significant dividend will hopefully flow for patients, families, and nephrologists alike.

Organisational culture: variation across hospitals and connection to patient safety climate

CONTEXT

Bureaucratic organisational culture is less favourable to quality improvement, whereas organisations with group (teamwork) culture are better aligned for quality improvement.

OBJECTIVE

To determine if an organisational group culture shows better alignment with patient safety climate.

DESIGN

Cross-sectional administration of questionnaires. Setting 40 Hospital Corporation of America hospitals.

PARTICIPANTS

1406 nurses, ancillary staff, allied staff and physicians.

MAIN OUTCOME MEASURES

Competing Values Measure of Organisational Culture, Safety Attitudes Questionnaire (SAQ), Safety Climate Survey (SCSc) and Information and Analysis (IA).

RESULTS

The Cronbach alpha was 0.81 for the group culture scale and 0.72 for the hierarchical culture scale. Group culture was positively correlated with SAQ and its subscales (from correlation coefficient r = 0.44 to 0.55, except situational recognition), ScSc (r = 0.47) and IA (r = 0.33). Hierarchical culture was negatively correlated with the SAQ scales, SCSc and IA. Among the 40 hospitals, 37.5% had a hierarchical dominant culture, 37.5% a dominant group culture and 25% a balanced culture. Group culture hospitals had significantly higher safety climate scores than hierarchical culture hospitals. The magnitude of these relationships was not affected after adjusting for provider job type and hospital characteristics.

CONCLUSIONS

Hospitals vary in organisational culture, and the type of culture relates to the safety climate within the hospital. In combination with prior studies, these results suggest that a healthcare organisation's culture is a critical factor in the development of its patient safety climate and in the successful implementation of quality improvement initiatives.

A note on some reinforcing properties of university lectures

Contingency management systems in university courses have sometimes assigned the role of reinforcing stimulus to lectures and demonstrations. Attending a lecture was made contingent upon having previously finished certain course assignments. The present paper investigated some variables that control student attendance at lectures. Attendance remained high throughout each course at those class meetings where quizzes contributing to course grades were given or where impending quizzes were discussed. Attendance at lectures over the reading assignments or over material unrelated to course quizzes rapidly declined. When students were given course credit for attending these lectures, or when the lectures included information for future quizzes, attendance increased. When attending these lectures was made contingent upon having completed certain assignments the prior week, no increase in assignment completion was noted and the attendance at the lectures decreased even further. All lectures were given during one class meeting each week. Attendance at the other class meetings during the week remained stable.

Monitoring Interfacial Bioelectrochemistry Using a FRET Switch

Generation of functionally active biomolecular monolayers is important in both analytical science and biophysical analyses. Our ability to monitor the redox-active state of immobilized proteins or enzymes at a molecular level, from which stochastic and surface-induced variations would be apparent, is impeded by comparatively slow electron-transfer kinetics and associated signal:noise difficulties. We demonstrate herein that by covalently tethering an appropriate dye to the copper protein azurin a highly oxidation-state-sensitive FRET process can be established which enables redox switching to be optically monitored at protein levels down to the zeptomolar limit. The surface-potential-induced cycling of emission enables the redox potential of clusters of a few hundred molecules to be determined.

A week of simulated night work delays salivary melatonin onset

In most studies, the magnitude and rate of adaptation to various night work schedules is assessed using core body temperature as the marker of circadian phase. The aim of the current study was to assess adaptation to a simulated night work schedule using salivary dim light melatonin onset (DLMO) as an alternative circadian phase marker. It was hypothesised that the night work schedule would result in a phase delay, manifest in relatively later DLMO, but that this delay would be somewhat inhibited by exposure to natural light. Participants worked seven consecutive simulated 8-hour night shifts (23:00-07:00 h). By night 7, there was a mean cumulative phase delay of 5.5 hours, equivalent to an average delay of 0.8 hours per day. This indicates that partial circadian adaptation occurred in response to the simulated night work schedule. The radioimmunoassay used in the current study provides a sensitive assessment of melatonin concentration in saliva that can be used to determine DLMO, and thus provides an alternative phase marker to core body temperature, at least in laboratory studies.

The effects of bright light and nighttime melatonin administration on cardiac activity

Although melatonin has an important physiological role in the facilitation of sleep, its precise mechanism of action is not clear. To investigate the potential contribution of melatonin to influence cardiac autonomic activity in the evening, 16 young healthy subjects participated in a repeated measures design where cardiac autonomic activity, heart rate and blood pressure were examined during three experimental conditions. An initial baseline condition involved dim light exposure (< 10 lux), permitting the normal nocturnal rise in endogenous melatonin. In other sessions, subjects were exposed to bright light (> 3000 lux) to suppress melatonin secretion and administered a placebo or melatonin (5 mg) capsule at the estimated time of increase in endogenous melatonin (wake time + 14 hours). Heart rate, pre-ejection period (a measure of cardiac sympathetic activity) and respiratory sinus arrhythmia (a measure of parasympathetic activity) were not significantly altered in response to the three melatonin levels. While melatonin had no effect on diastolic blood pressure, systolic blood pressure was maximally decreased by 6 +/- 1.93 mmHg (mean +/- SEM, p < 0.005) 150 minutes after exogenous melatonin. The results indicate that melatonin does not directly modulate cardiac autonomic activity, but may rather act directly on the cardiovascular system.