Étude SeroCOVIDial : évaluation de la séroprévalence SARS-CoV2 chez les patients hémodialysés chroniques et leurs soignants après la 1re vague et avant la campagne vaccinale, une étude de cohorte

Introduction

Les patients hémodialysés chroniques (HD) constituent une population à haut risque de COVID-19 sévère, et ne peuvent rester confinés. La prévalence de l’immunisation contre le SARS-CoV-2 parmi les patients HD et les soignants, après la première vague de COVID-19 et avant la campagne de vaccination, reste inconnue.

Description

PHRC inter-régional, étude de cohorte prospective réalisée entre juin et décembre 2020 dans 4 grands centres de dialyse d’Aix–Marseille (dépistage systématique des symptômes et mesures d’isolement des malades infectés dès le début de la pandémie).

Méthodes

Séroprévalence SARS-CoV2 évaluée par test sérologique rapide (Biosynex®) chez les patients et leurs soignants en juin (M0), septembre(M3) et décembre (M6) 2020.

Résultats

En juin 2020, 451 patients HD et 238 soignants ont été inclus. La séroprévalence SARS-CoV2 à M0 était de 8,4 % chez les patients et 6,7 % chez les soignants. Parmi les participants immunisés, 26,3 % des patients et 6,3 % des soignants n’avaient présenté aucun symptôme de COVID-19. Parmi les participants ayant eu une infection SARS-CoV2 documentée avant M0, 87 % des patients et 90 % des soignants étaient immunisés à M0. La séroprévalence est restée stable à M3, et a augmenté à M6 lors de la 2^e vague épidémique, atteignant 13,8 % des patients et 12,6 % des soignants. À M6, 38 (8,4 %) patients étaient décédés dont 9 (2 %) de COVID-19, et 12 autres ont été hospitalisés pour COVID-19. Deux patients immunisés à M0 ont présenté une COVID-19 non sévère au cours du suivi.

Conclusion

Dans cette large cohorte de patients HD et de soignants, la prévalence de l’immunisation SARS-CoV2 après la première vague épidémique était relativement faible, ce qui reflète probablement l’efficacité des mesures de protection mises en place. L’immunisation n’était pas toujours persistante chez les participants, et certains patients immunisés à M0 ont pu être infectés, ce qui souligne l’intérêt de la vaccination systématique de cette population.

Drop spreading and gelation of thermoresponsive polymers

Spreading and solidification of liquid droplets are elementary processes of relevance for additive manufacturing. Here we investigate the effect of heat transfer on spreading of a thermoresponsive solution (Pluronic F127) that undergoes a sol-gel transition above a critical temperature Tm. By controlling the concentration of Pluronic F127 we systematically vary Tm, while also imposing a broad range of temperatures of the solid and the liquid. We subsequently monitor the spreading dynamics over several orders of magnitude in time and determine when solidification stops the spreading. It is found that the main parameter is the difference between the substrate temperature and Tm, pointing to a local mechanism for arrest near the contact line. Unexpectedly, the spreading is also found to stop below the gelation temperature, which we attribute to a local enhancement in polymer concentration due to evaporation near the contact line.

Neuraxial analgesia is not associated with an increased risk of post-partum relapses in MS

Background:

Obstetrical analgesia remains a matter of controversy because of the fear of neurotoxicity of local anesthetics on demyelinated fibers or their potential relationship with subsequent relapses.

Objective:

To assess the impact of neuraxial analgesia on the risk of relapse during the first 3 months post-partum, with a focus on women who experienced relapses during pregnancy.

Methods:

We analyzed data of women followed-up prospectively during their pregnancies and at least 3 months post-partum, collected in the Pregnancy in Multiple Sclerosis (PRIMS) and Prevention of Post-Partum Relapses with Progestin and Estradiol in Multiple Sclerosis (POPARTMUS) studies between 1992–1995 and 2005–2012, respectively. The association of neuraxial analgesia with the occurrence of a post-partum relapse was estimated by logistic regression analysis.

Results:

A total of 389 women were included, 215 from PRIMS and 174 from POPARTMUS. In total, 156 women (40%) had neuraxial analgesia. Overall, 24% experienced a relapse during pregnancy and 25% in the 3 months post-partum. Women with a pregnancy relapse were more likely to have a post-partum relapse (odds ratio (OR) = 1.83, p = 0.02), independently of the use of neuraxial analgesia. There was no association between neuraxial analgesia and post-partum relapse (OR = 1.08, p = 0.78).

Conclusion:

Neuraxial analgesia was not associated with an increased risk of post-partum relapses, whatever multiple sclerosis (MS) activity during pregnancy.

In Vivo Accumulation of Sodium Pump Inhibitor by Normal and Uremic Erythrocytes

A uremic toxin fraction (fraction 2-3-1) in the middle molecular mass range (300-2000 Da) containing a sodium potassium inhibitor pump was studied. As fraction 2-3-1 was known to be present in minute quantities in urine and plasma, erythrocyte lysates were used as an alternative source. Results show that fraction 2-3-1 is more abundant in erythrocytes than in normal urine. In addition, the fraction is present in a greater quantity in uremic erythrocytes than in normal blood cells. It is concluded that fraction 2-3-1 is concentrated at the erythrocyte level in uremic patients

Uremic Toxicity: Present State of the Art

The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal condition are excreted by the healthy kidneys (uremic toxins). In the area of identification and characterization of uremic toxins and in the knowledge of their pathophysiologic importance, major steps forward have been made during recent years. The present article is a review of several of these steps, especially in the area of information about the compounds that could play a role in the development of cardiovascular complications. It is written by those members of the Uremic Toxins Group, which has been created by the European Society for Artificial Organs (ESAO). Each of the 16 authors has written a state of the art in his/her major area of interest.

A reliable method to assess the water permeability of a dialysis system: the global ultrafiltration coefficient

Background

Recent randomized controlled trials suggest that sufficiently high convection post-dilutional haemodiafiltration (HC-HDF) improves survival in dialysis patients, consequently this technique is increasingly being adopted. However, when performing HC-HDF, rigorous control systems of the ultrafiltration setting are required. Assessing the global ultrafiltration coefficient of the dialysis system [GKD-UF; defined as ultrafiltration rate (QUF)/transmembrane pressure] or water permeability may be adapted to the present dialysis settings and be of value in clinics.

Methods

GKD-UF was determined and its reproducibility, variability and influencing factors were specifically assessed in 15 stable patients routinely treated by high-flux haemodialysis or HC-HDF in a single unit.

Results

GKD-UF invariably followed a parabolic function with increasing QUF in dialysis and both pre- and post-dilution HC-HDF (R2 constantly >0.96). The vertex of the parabola, GKD-UF-max and related QUF were very reproducible per patient (coefficient of variation 3.9 ± 0.6 and 3.3 ± 0.3%, respectively) and they greatly varied across patients (31–42 mL/h−1/mmHg and 82–100 mL/min, respectively). GKD-UF-max and its associated QUF decreased during dialysis treatment (P < 0.01). The GKD-UF-max decrease was related to weight loss (R2 = 0.66; P = 0.0015).

Conclusions

GKD-UF is a reliable and accurate method to assess the water permeability of a system in vivo. It varies according to dialysis setting and patient-related factors. It is an objective parameter evaluating the forces driving convection and identifies any diversion of the system during the treatment procedure. It is applicable to low- or high-flux dialysis as well as pre- or post-dilution HDF. Thus, it may be used to describe the characteristics of a dialysis system, is suitable for clinical use and may be of help for personalized prescription.

Dynamics of sessile and pendant drops excited by surface acoustic waves: Gravity effects and correlation between oscillatory and translational motions

When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed, the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or, more generally, by an initial or dynamically induced stretching of the drop. In turn, we elucidate the origin of the resonance frequency shift, as well as the origin of the strong correlation between oscillatory and translational motion. We show that for sessile drops, the velocity is mainly determined by the amplitude of oscillation and that the saturation observed is due to the nonlinear dependence of the drop response frequency on the dynamically induced stretching.

Universality of tip singularity formation in freezing water drops

A drop of water deposited on a cold plate freezes into an ice drop with a pointy tip. While this phenomenon clearly finds its origin in the expansion of water upon freezing, a quantitative description of the tip singularity has remained elusive. Here we demonstrate how the geometry of the freezing front, determined by heat transfer considerations, is crucial for the tip formation. We perform systematic measurements of the angles of the conical tip, and reveal the dynamics of the solidification front in a Hele-Shaw geometry. It is found that the cone angle is independent of substrate temperature and wetting angle, suggesting a universal, self-similar mechanism that does not depend on the rate of solidification. We propose a model for the freezing front and derive resulting tip angles analytically, in good agreement with the experiments.

Survival of patients with ANCA-associated vasculitis on chronic dialysis: data from the French REIN registry from 2002 to 2011

BACKGROUND

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) can lead to end-stage renal disease in patients with renal involvement.

OBJECTIVE

This study evaluated the survival of AAV patients on chronic dialysis in France.

METHODS

Between 2002 and 2011, a total of 425 AAV patients started chronic dialysis and were registered in the Renal Epidemiology and Information Network. We analysed survival censored for renal transplantation, recovery of renal function and loss to follow-up. AAV patients were compared with 794 matched non-AAV patients on chronic dialysis.

RESULTS

A total of 166 (39%) patients with microscopic polyangiitis and 259 (61%) patients with granulomatosis with polyangiitis were registered. Within a median follow-up of 23 months, 58 (14%) patients received a renal allograft and 19 (4%) recovered renal function. Median survival on dialysis was 5.35 years (95% CI, 4.4-6.3) and survival rates at 3 months, 1, 3 and 5 years were 96%, 85%, 68% and 53%, respectively. A total of 143 (41%) patients died after a median of 16 months. Causes of death were cardiovascular (29%), infections (20%), malnutrition (13%), malignancies (4%), AAV relapse (2%), miscellaneous (14%) and unknown (18%). Multivariate logistic regression identified three independent risk factors associated with AAV patients' mortality: age (HR = 1.05/year, P < 0.001), peripheral artery disease (HR = 2.62, P = 0.003) and frailty (HR = 2.43, P < 0.001). Survival of AAV patients did not differ from non-AAV controls, but infectious mortality was higher in AAV patients (20% vs. 8%, P < 0.001).

CONCLUSION

Survival of AAV patients in chronic dialysis, although poor, was comparable to survival of non-AAV controls on dialysis. There was a similar burden of cardiovascular mortality, but higher infectious mortality.