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SARS-CoV-2 infection can cause severe placental lesions leading rapidly to intra uterine fetal death (IUFD). From August 2020 to September 2021, in the pathology Department of Toulouse Oncopole, we analyzed 50 placentas from COVID-19 positive unvaccinated mothers. The purpose of our study is to describe the clinicopathological characteristics of these placental damages and to understand the pathophysiology. Ten of them (20%) showed placental lesions with positive immunohistochemistry for SARS-CoV-2 in villous trophoblast. In five cases (10%), we observed massive placental damage associating trophoblastic necrosis, fibrinous deposits, intervillositis as well as extensive hemorrhagic changes due to SARS-CoV-2 infection probably responsible of IUFD by functional placental insufficiency. In five other cases, we found similar placental lesions but with a focal distribution that did not lead to IUFD but live birth. These lesions are independent of maternal clinical severity of COVID-19 infection since they occur despite mild maternal symptoms and are therefore difficult to predict. In our cases, they occurred 1 to 3 weeks after positive SARS-CoV-2 maternal RT-PCR testing and were observed in 2nd and 3rd trimesters of pregnancies. When these lesions are focal, they do not lead to IUFD and can be involved in intra-uterine growth restriction. Our findings, together with recent observations, suggest that future pregnancy guidance should include stricter pandemic precautions such as screening for a wider array of COVID-19 symptoms, enhanced ultrasound monitoring as well as newborn medical surveillance.

ABSTRACIModifications of cytoplasmic pH in Acer pseudoplatanus L. cells cultivated in suspension have been induced by acid-loads and studied by using 31P nuclear magnetic resonance spectroscopy. The initial drop of cytoplasmic pH, observed in the first minutes of exposure to weak lipophilic acids, was followed by a slow recovery to reach a plateau phase with a pH value lower than the initial one. Conversely, removal of the acid led to a sharp increase of cytoplasmic pH with in most cases an overshoot toward more alkaline values than the initial one and a subsequent decrease to more acidic values. This shows that A. pseudoplatanus cells powerfully regulate their cytoplasmic pH both on the acid side of their normal pH, during the acid-load, and on the alkaline side, after removal of acid. Similar results were obtained with different types of acid-loads, i.e. treatments with propionic or benzoic acid or bubbling with C02-enriched air. This indicates that the occurrence of pH regulation does not depend upon the method used to acid-load the cells. The time courses of cytoplasmic pH observed for A. pseudoplatanus and also Catharanthus roseus cells are similar to those recorded for animal cells but different from those described for other plant materials for which no recovery phase was observed. This can be explained by different balances between the initial rate of proton influx brought in by the acids, and the capacity of proton consumption by the regulatory mechanisms. The existence of the recovery phase offers a unique possibility to study the regulation of the cytoplasmic pH of plant cells, as it has been done in animal systems.The study of transient changes in pHi2 has brought considerable progress in the understanding of pHi regulation in animal cells (27) (7), and root hair cells from Sinapis alba (2). During the last few years, the 3P NMR technique has been adapted to plant material, allowing simultaneous determinations of vacuolar and cytoplasmic pH values (24). The hypoxic acidification of the cytoplasm of maize root tips under hypoxia has been very elegantly studied by Roberts et al. (22,23). These authors used acetic acid (22) and CO2 (23) as acidifying agents and demonstrated large cytoplasmic acidifications.The effects of acid-loads have been also indirectly studied (i.e.without measuring the pH, by their effect on the electrogenic proton pump at the plasmalemma and the subsequent modifications of ionic exchanges. Weak acids like butyric acid induce a hyperpolarization associated with a K+ influx in maize roots (18). Butyric and benzoic acids hyperpolarize oat coleoptiles (1).These results are in good agreement with more recent ones associating pH and potential measurements with microelectrodes in maize (7) and S. alba roots (2) which demonstrate unambiguously that the hyperpolarization is a consequence of cytoplasmic acidification. Acid-loading of plant cells now appears to be as a useful tool to stimulate the plasmalemma proton pump (1,7,18,28) and to study the relationship between pH, and growth (7).W...

Pseudoamniotic band syndrome is a rare complication that occurs after invasive procedures for complicated monochorionic twins. We report 2 cases of intrauterine recipient fetal death after laser therapy for twin-twin transfusion syndrome due to umbilical cord constriction by the amniotic band.

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