Risk assessment of airborne COVID-19 exposure in social settings.

The COVID-19 pandemic has led to many countries oscillating between various states of lock-down as they seek to balance keeping the economy and essential services running and minimizing the risk of further transmission. Decisions are made about which activities to keep open across a range of social settings and venues guided only by ad hoc heuristics regarding social distancing and personal hygiene. Hence, we propose the dual use of computational fluid dynamic simulations and surrogate aerosol measurements for location-specific assessment of risk of infection across different real-world settings. We propose a 3-tiered risk assessment scheme to facilitate classification of scenarios into risk levels based on simulations and experiments. Threshold values of <54 and >840 viral copies and <5% and >40% of original aerosol concentration are chosen to stratify low, medium, and high risk. This can help prioritize allowable activities and guide implementation of phased lockdowns or re-opening. Using a public bus in Singapore as a case study, we evaluate the relative risk of infection across scenarios such as different activities and passenger positions and demonstrate the effectiveness of our risk assessment methodology as a simple and easily interpretable framework. For example, this study revealed that the bus's air-conditioning greatly influences dispersion and increases the risk of certain seats and that talking can result in similar relative risk to coughing for passengers around an infected person. Both numerical and experimental approaches show similar relative risk levels with a Spearman's correlation coefficient of 0.74 despite differing observables, demonstrating applicability of this risk assessment methodology to other scenarios.

Novel GATA6 loss-of-function mutation responsible for familial atrial fibrillation.

Atrial fibrillation (AF) is the most commonly sustained cardiac arrhythmia, and confers a substantially increased risk of morbidity and mortality. Increasing evidence has indicated that hereditary defects are implicated in AF. However, AF is genetically heterogeneous and the genetic etiology of AF in a significant portion of patients remains unclear. In this study, the entire coding sequence and splice junctions of the GATA6 gene, which encodes a zinc-finger transcription factor crucial for cardiogenesis, were sequenced in 140 unrelated patients with lone AF. The available relatives of the index patient carrying an identified mutation and 200 unrelated ethnically-matched healthy individuals used as the controls were genotyped. The functional characteristics of the mutant GATA6 were assessed in contrast to its wild-type counterpart using a luciferase reporter assay system. As a result, a novel heterozygous GATA6 mutation, p.G469V, was identified in a family with AF inherited in an autosomal dominant pattern. The mutation was absent in the 200 control individuals and the altered amino acid was completely conserved across species. Functional analysis demonstrated that the GATA6 mutation was associated with a significantly decreased transcriptional activity. The findings provide novel insight into the molecular mechanism involved in the pathogenesis of AF, as well as insight into potential therapies for the prevention and treatment of AF.

[The influence of positive end-expiratory pressure on central venous pressure in patients with severe craniocerebral injury].

OBJECTIVE: To observe the impact of positive end-expiratory pressure (PEEP) on central venous pressure (CVP) in mechanically ventilated patients with severe craniocerebral injury. METHODS: A prospective, interventional, self-control study was conducted. Thirty severe craniocerebral injury patients with central respiratory failure were enrolled. The changes in CVP, mean arterial pressure (MAP), heart rate (HR) and pulse oxygen saturation [SpO2] were monitored at different PEEP levels [0, 3, 6, 9, 12, 15 cm H2O; 1 cm H2O=0.098 kPa] during mechanical ventilation and after weaning of mechanical ventilation. The influences of PEEP and its discontinuance on haemodynamics and oxygenation were analyzed. RESULTS: The values of CVP [cm H2O] were increased when PEEP increased (from 7.9±3.1 to 13.1±3.7), a linear correlation was found (R=0.509, P=0.000), and linear regression equation was CVP [cm H2O]=7.774+0.368×PEEP [cm H2O]; CVP was elevated about 0.368 cm H2O when PEEP increased 1 cm H2O. CVP values significantly decreased during discontinuance of mechanical ventilation, as compared to those measured at different PEEP levels during mechanical ventilation (F=24.429, P=0.000). The values of MAP, HR and SpO2 showed no significant change with increase of PEEP levels [MAP (mm Hg, 1 mm Hg=0.133 kPa): from 81.6±10.4 to 85.6±10.6; HR (beats per minute): from 79.9±13.5 to 88.1±15.4; SpO2: from 0.968±0.036 to 0.975±0.033, all P>0.05] in mechanically ventilated patients, but discontinuance of mechanical ventilation could significantly increase the levels of MAP and HR (95.3±8.4 and 94.9±10.3, respectively) and lower SpO2 levels (0.928±0.036, all P=0.000). CONCLUSIONS: CVP values were overestimated during an increase in PEEP in mechanically ventilated patients with severe craniocerebral injury. CVP was increased about 0.368 cm H2O following an increase of PEEP of 1 cm H2O, whereas the values of MAP, HR and SpO2 showed no significant change with increase in PEEP levels. This study could offer a theoretical base in the correct assessment of CVP values at different PEEP levels without discontinuation of mechanical ventilation.

[Responses of spring corn growth and yield in a cold area of China to field warming at nighttime during pre-anthesis stage].

By using the facility for increasing free air temperature, a field experiment was conducted in a cold area of Northeast China to study the responses of the growth and yield of rain-fed spring corn to the field warming at nighttime during pre-anthesis stage. Under the field warming at nighttime, the nighttime temperature in 0-10 cm soil layer increased by 1.7 degrees C, and the soil moisture content had a slight decrease. Nighttime warming advanced the spring corn phenophases obviously, shorted the pre-anthesis phase by 1 day, and prolonged the post-anthesis phase by 1 day. Nighttime warming also promoted the corn seedlings growth and the root length. Comparing with those in un-warming treatment, green leaf area and three-ear-leave area in nighttime warming treatment increased by 13.5% and 14.6%, and the aboveground biomass, grain yield, and 100-grain mass increased significantly by 8.2%, 9.3%, and 7.1%, respectively. It was suggested that the climate warming (especially the nighttime warming) in Northeast China could improve spring corn growth, and directly affect the corn yield.

Huge gastric disopyrobezoar: a case report and review of literatures.

We reported a case of huge gastric phytobezoar. The gastric phytobezoar was successfully removed through gastrotomy after two failed attempts in endoscopic fragmentation and removal. Disopyrobezoars could be treated either conservatively or surgically. Gastrotomy or laparoscopical management is recommended for the treatment of huge disopyrobezoars.