Remdesivir and Mortality in Patients with COVID-19

Background

The impact of remdesivir (RDV) on mortality rates in coronavirus disease 2019 (COVID-19) is controversial, and the mortality effect in subgroups of baseline disease severity has been incompletely explored. The purpose of this study was to assess the association of RDV with mortality rates in patients with COVID-19.

Methods

In this retrospective cohort study we compared persons receiving RDV with those receiving best supportive care (BSC). Patients hospitalized between 28 February and 28 May 2020 with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection were included with the development of COVID-19 pneumonia on chest radiography and hypoxia requiring supplemental oxygen or oxygen saturation ≤94% with room air. The primary outcome was overall survival, assessed with time-dependent Cox proportional hazards regression and multivariable adjustment, including calendar time, baseline patient characteristics, corticosteroid use, and random effects for hospital.

Results

A total of 1138 patients were enrolled, including 286 who received RDV and 852 treated with BSC, 400 of whom received hydroxychloroquine. Corticosteroids were used in 20.4% of the cohort (12.6% in RDV and 23% in BSC). Comparing persons receiving RDV with those receiving BSC, the hazard ratio (95% confidence interval) for death was 0.46 (.31–.69) in the univariate model (P < .001) and 0.60 (.40–.90) in the risk-adjusted model (P = .01). In the subgroup of persons with baseline use of low-flow oxygen, the hazard ratio (95% confidence interval) for death in RDV compared with BSC was 0.63 (.39–1.00; P = .049).

Conclusion

Treatment with RDV was associated with lower mortality rates than BSC. These findings remain the same in the subgroup with baseline use of low-flow oxygen.

Neurophysiological and behavioral effects of a 60 Hz, 1,800 μT magnetic field in humans

The effects of time-varying magnetic fields (MF) on humans have been actively investigated for the past three decades. One important unanswered question is the potential for MF exposure to have acute effects on human biology. Different strategies have been used to tackle this question using various physiological, neurophysiological and behavioral indicators. For example, researchers investigating electroencephalography (EEG) have reported that extremely low frequency (ELF, <300 Hz) MF can increase resting occipital alpha rhythm (8-12 Hz). Interestingly, other studies have demonstrated that human motricity can be modulated by ELF MF: a reduction of anteroposterior standing balance or a decrease of physiological tremor intensity have been reported as consequences of exposure. However, the main limitation in this domain lies in the lack of results replication, possibly originating from the large variety of experimental approaches employed. Therefore, the present study aimed to investigate the effects of a 60 Hz, 1,800 μT MF exposure on neurophysiological (EEG) and neuromotor (standing balance, voluntary motor function, and physiological tremor) aspects in humans using a single experimental procedure. Though results from this study suggest a reduction of human standing balance with MF exposure, as well as an increase of physiological tremor amplitude within the frequency range associated with central nervous system contribution, no exposure effect appeared on other investigated parameters (e.g., EEG or voluntary motor control). These results suggest that 1 h of 60 Hz, 1,800 μT MF exposure may modulate human involuntary motor control without being detected in the cortical electrical activity.

A magnetic field exposure facility for evaluation of animal carcinogenicity

Several animal studies have been carried out at the Institut Armand Frappier (IAF) to determine whether chronic exposure to 60 Hz linearly polarized sinusoidal magnetic fields might increase the risk of cancer development of female Fisher rats. The magnetic field exposure facility was developed to meet the requirements of the study protocol for chronic exposure of large number of animals to field intensities of sham < 0.2 microT, 2 microT, 20 microT, 200 microT, and 2000 microT. At each exposure level, including sham, the animals are distributed in a group of four exposure units. Each exposure unit contains two exposure volumes having uniform distribution of magnetic fields for the animals, while the magnetic field external to the unit falls off rapidly due to the "figure-eight" coil topography used. A program of "shake down" tests, followed by verification and calibration of the exposure facility, was carried out prior to starting the animal experiments. Continuous monitoring of the magnetic field and other environmental parameters was an important part in the overall quality assurance program adopted.

Spawning success in the damselfish Amblyglyphidodon leucogaster: the influence of eggs in the nest

Spawning success of males and its correlates were investigated in a natural colony of whitebelly damselfish, A. leucogaster (Pomacentridae), to explore the criteria that females use in choosing mates. The mating success of individual males was variable, with some males acquiring as few as 5000 eggs and others as many as 450 000 eggs during a breeding season. Male spawning success was not correlated with body size, territory size, nest site parameters or parental care behaviour. Egg hatching success was not related to either male size or egg clutch size, and all males were capable of rearing eggs to hatching. The temporal sequence of choices by females indicated non-independent choice by females, such that males chosen by females on the first spawn of the day were also chosen by females that spawned later in the day. Field observations indicated that, in the absence of male courtship, females preferentially visited males that had eggs in their nest site. Males that had recently mated were preferred by females over those males with either late-stage eggs or no eggs in the nest. This female preference did not appear to be related to increased paternal care or egg clutch survival. Given that the mating system is promiscuous and non-resource based, and that there appears to be little difference among males in body size, females may be mating non-independently by mimicking the choice of other females. Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

Human perception of electric fields and ion currents associated with high-voltage DC transmission lines

The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.

[From miasmata to germs. The impact of bacteriology on medical practice in Canadian territory from 1870 to 1930]

This article analyzes some aspects concerning the introduction of bacteriological theory and practice into Canadian territory from 1870 to 1930. The author begins by presenting the principal explanatory models characterizing the transition period from pre-bacteriological discourse--referring to infectious diseases and surgical infections--to new bacteriological paradigms. He goes on to analyze the different ways in which the germ theory and then bacteriology spread into Canadian territory. The transition periods, where old and new coexisted, reveal a kind of syncretism by physicians in relation to both aetiology of infectious diseases and surgical procedures. The author then shows that there were two distinct phases in the overall context of the history of antiseptic surgery from 1868 to 1890. He demonstrates that the use of antiseptics did not necessarily mean either adherence to Pasteur's postulates on fermentation or strict observance of Listerian methods. Finally, the article expounds on the role played by European institutions in importing bacteriological knowledge and institutionalizing this new discipline in Canadian territory.

Demineralization potential of different concentrations of gelatinized wheat starch

Six subjects wore intraoral devices carrying bovine enamel blocks covered with a layer of Streptococcus mutans. They swished solutions of 5% glucose or maltose, or sols or gels of 3, 5, 10, 15, or 20% gelatinized wheat starch in the mouth for 3 X 1 min. Demineralization was measured after 45 min by determining the change in iodide permeability (delta Ip) of the enamel. Spittings of the administered materials and samples of saliva, taken at intervals during the test, were analyzed for maltose, and the time of clearance was calculated. Demineralization was greatest for glucose followed by maltose, the starch gels, and the sols. The latter gave close to zero scores. The salivary clearance time increased with increase in concentration of the starch. Although the starch was hydrolyzed rapidly in the mouth, its oral retentiveness was greater than that of the maltose rinse. Demineralization was closely correlated with the final pH of the S. mutans cell layer. The data indicate that the starch in baked or cooked foods may have a significant demineralization potential and that it enhances oral retentiveness.

Enamel demineralization and the length of intra-oral exposure to different concentrations of glucose or sucrose

Six subjects wore intra-oral devices carrying eight bovine enamel blocks which were covered with a layer of S. mutans. They rinsed their mouths for five sec, one min, or multiples of one min with a 5 or 10% glucose (G) solution. Demineralization was measured after 45 min by determining the change in iodide permeability (delta Ip) of the enamel. In addition, saliva samples, taken at intervals during the test, were analyzed for G, and the time of clearance (tc) was calculated. Demineralization scores (delta Ip) were consistently greater from the 10% than from the 5% G solution. Both solutions produced an increase in delta Ip with an increase in the rinsing time (tr). The G remaining in saliva after the rinse did not significantly affect delta Ip. The delta Ip scores showed good correlation with the final pH of the S. mutants cell mass, r = -0.77. For each rinse solution, the scores also showed good correlations with tr (r = 0.87 and 0.79) and much weaker correlations with tr + tc (r = 0.44 and 0.53). Continuous in vitro exposure to 1, 5, or 10% solutions of sucrose (S) in saliva for 30 min or more caused a linear increase in delta Ip with time with no concentration effects. A linear increase was also observed in vivo when a one-minute mouth-rinse with 10% solution of S was administered every 30 min. The findings indicate that significant demineralization may occur while carbohydrate foods are consumed, and that brushing the teeth or rinsing the mouth after meals may not be as effective against caries as is generally believed.

Sugar clearance from saliva and intra-oral spaces

The clearance of glucose from saliva was compared with that from spaces located in an intra-oral appliance. The spaces (N = 8) were similar in shape and size to posterior interdental spaces and could be sampled with a microsyringe without removing the appliance from the mouth. The subjects (N = 5) rinsed their mouths with solutions of 5, 10, or 25% glucose. Samples were obtained from a pair of spaces and from saliva at standard intervals and were analyzed for glucose. The rate of glucose clearance was consistently slower from the spaces than from bulk saliva, as shown by higher concentrations and longer clearance times for the spaces. The clearance curves were similar in shape and were rectilinear when the logarithms of the concentrations were plotted against time. The rate of clearance from the spaces appears to be characteristic for an individual, as was also true of salivary clearance.

Effect of some salts of calcium, sodium, potassium, and strontium on intra-oral enamel demineralization

A newly-developed intra-oral enamel demineralization test was used to evaluate the effect of supplementation of a 10% sucrose solution with various components on enamel demineralization induced by the sucrose. Five human subjects wore a palatal prosthesis holding eight blocks of subsurface bovine enamel covered with a layer of S. mutans cells. The test involved rinsing with sucrose solution or with sucrose solution supplemented with 0.162 mol/l of different calcium salts or equivalent concentrations of Na-, K-, and Sr salts; rinsing was for one min at times zero and 45 min of the 90-minute test period. Ca-propionate, Ca-acetate, and Ca-levulinate completely inhibited sucrose-induced enamel demineralization; Ca-chloride, Ca-lactate, and Ca-ascorbate gave from 65-75%, and K-acetate, Na-lactate, and Sr-lactate 39, 25, and 18% inhibition, respectively. Consideration of the anion dissociation constants and the Ca-anion association constants of the salts suggests that the observed inhibition is caused mainly by common ion effects and, to a lesser extent, by buffer effects.