m-NLP Inference Models Using Simulation and Regression Techniques.

Current inference techniques for processing multi-needle Langmuir probe (m-NLP) data are often based on adaptations of the Orbital Motion-Limited (OML) theory which relies on several simplifying assumptions. Some of these assumptions, however, are typically not well satisfied in actual experimental conditions, thus leading to uncontrolled uncertainties in inferred plasma parameters. In order to remedy this difficulty, three-dimensional kinetic particle in cell simulations are used to construct a synthetic data set, which is used to compare and assess different m-NLP inference techniques. Using a synthetic data set, regression-based models capable of inferring electron density and satellite potentials from 4-tuples of currents collected with fixed-bias needle probes similar to those on the NorSat-1 satellite, are trained and validated. The regression techniques presented show promising results for plasma density inferences with RMS relative errors less than 20%, and satellite potential inferences with RMS errors less than 0.2 V for potentials ranging from -6 to -1 V. The new inference approaches presented are applied to NorSat-1 data, and compared with existing state-of-the-art inference techniques.

Genetics of symptom remission in outpatients with COVID-19.

We conducted a genome-wide association study of time to remission of COVID-19 symptoms in 1723 outpatients with at least one risk factor for disease severity from the COLCORONA clinical trial. We found a significant association at 5p13.3 (rs1173773; P = 4.94 × 10-8) near the natriuretic peptide receptor 3 gene (NPR3). By day 15 of the study, 44%, 54% and 59% of participants with 0, 1, or 2 copies of the effect allele respectively, had symptom remission. In 851 participants not treated with colchicine (placebo), there was a significant association at 9q33.1 (rs62575331; P = 2.95 × 10-8) in interaction with colchicine (P = 1.19 × 10-5) without impact on risk of hospitalisations, highlighting a possibly shared mechanistic pathway. By day 15 of the study, 46%, 62% and 64% of those with 0, 1, or 2 copies of the effect allele respectively, had symptom remission. The findings need to be replicated and could contribute to the biological understanding of COVID-19 symptom remission.

Clinical implementation of a scrubless chlorhexidine/ethanol pre-operative surgical hand rub.

The objective of surgical scrubbing is to reduce the bioburden on the hands of the surgical team in hope that if gloves are punctured or torn, the number of bacteria released at the operation site will be minimal and therefore reduce the risk of site infection. Long procedures with scrubbing and soaping can, however, be counterproductive because with repetition they tend to cause skin abrasions, damages and injuries without further reducing the risk of bacterial release. Within a general review of OR processes, it was decided to substitute to the standard surgical scrub a "new" scrubless pre-op surgical hand rub procedure. This article summarizes the results.

Absence of association between infectious agents and endothelial function in healthy young men.

BACKGROUND: Although several studies have reported correlations between infections and coronary artery disease, associations with endothelial dysfunction, its precursor, have not been established. This study assessed whether infection with Chlamydia pneumoniae (CP), cytomegalovirus (CMV), Epstein-Barr virus (EBV), or Helicobacter pylori (HP) is associated with decreased endothelial function. METHODS AND RESULTS: Sixty-five male subjects, aged 20 to 45 years, with no risk factors or known coronary artery disease were enrolled in a seroepidemiological cross-sectional study. Endothelial function was determined by flow-mediated brachial vasodilation. Serum antibodies consisting of anti-CP IgG and IgM, anti-CMV IgG, anti-EBV nuclear antigen, and anti-HP IgG and markers of inflammation including high-sensitivity C-reactive protein were measured. Average age was 29.3+/-5.5 years. Seroprevalence values were 65.1%, 34.9%, 88.9%, and 14.3% for CP, CMV, EBV, and HP, respectively. Average values for endothelium-dependent and -independent vasodilation were 9.4+/-4.5% and 12.6+/-5.0%. Despite adequate statistical power (82% for the primary end point), no association between endothelial function and seropositivity to individual infectious agents, infectious burden, or C-reactive protein was observed in regression analyses controlling for variables including age, blood pressure, and lipid parameters. Moreover, no dose-response trends between serum titers and endothelial function were found. CONCLUSIONS: Lack of association between chronic infection with CP, CMV, EBV, HP, or pathogen burden and endothelial function was observed, suggesting that these agents are not implicated as early etiologic triggers in the genesis of coronary artery disease. These results do not preclude active involvement at later stages of the pathophysiological process, such as acceleration of existing atherosclerosis and acute plaque rupture.

Methicillin-resistant Staphylococcus aureus infection in a cardiac surgical unit.

BACKGROUND: Increased antibiotic resistance of common bacteria is attributed in part to the widespread use of various antibiotic agents. Prophylactic and therapeutic antibiotic treatments are routinely used in cardiac surgical units, and it is no surprise that methicillin-resistant Staphylococcus aureus infection is becoming a major cause of surgical infections in cardiac patients. METHODS: We reviewed our experience with patients who underwent cardiac surgery and experienced infection caused by methicillin-resistant Staphylococcus aureus. Between 1992 and 2000 at the Montreal Heart Institute, 39 patients had methicillin-resistant Staphylococcus aureus surgical infections, and 13,199 patients underwent cardiac surgery. The yearly incidence of methicillin-resistant Staphylococcus aureus infection, the relative risk of acute mediastinitis and of superficial wound infections or other types of methicillin-resistant Staphylococcus aureus infection episodes, and the effect of preventive measures were analyzed. RESULTS: The annual incidence of methicillin-resistant Staphylococcus aureus acute mediastinitis decreased from 0.37% (5/1321) of cardiac patients in 1992 and 0.44% (6/1355) in 1993 to 0% between 1994 and 1997, 0.13% (2/1528) in 1999, and 0% (0/1700) in 2000. The total incidence of methicillin-resistant Staphylococcus aureus infection, including mediastinitis, superficial and deep sternal and leg wound infection, and all systemic infection episodes ranged from 0.68% of patients in 1992 and 0.96% of patients in 1993 to 0.46% of patients in 1999 and 0.53% of patients in 2000. The relative risk of severe mediastinal methicillin-resistant Staphylococcus aureus infection to all other methicillin-resistant Staphylococcus aureus infection episodes decreased from 1.65 in 1992 to 0.41 in 1999 and 0 in 2000. Beginning in 1993, all patients given a diagnosis methicillin-resistant Staphylococcus aureus infection and all nasal carriers of methicillin-resistant Staphylococcus aureus were strictly isolated on the surgical unit, and vancomycin was used as the prophylactic antibiotic agent for cardiac surgery in these patients. Moreover, since 1998, all patients admitted in the hospital were screened, and nasal carriers were isolated and treated with topical antibiotic ointment. CONCLUSION: Mediastinal and other infections caused by methicillin-resistant Staphylococcus aureus have a significant morbidity in cardiac surgical patients. After an outbreak of methicillin-resistant Staphylococcus aureus mediastinal infections, several preventive measures to control methicillin-resistant Staphylococcus aureus contamination of surgical patients were implemented (nasal screening, preventive isolation, application of mupirocin, prophylaxis with vancomycin and alcohol gels) and were effective in decreasing the incidence of methicillin-resistant Staphylococcus aureus infection and mediastinitis after cardiac surgery.