Prompt and unavoidable requalification of ordinary hospital wards into a centralized department characterized by high-intensity treatment due to COVID-19 epidemic: the experience of Romano di Lombardia Hospital.

The Coronavirus epidemic quickly spread in Italy from China. In particular, it affected Bergamo province where Romano di Lombardia hospital is situated. Therefore, this hospital felt the urgency to requalify its activity in no time. It transformed itself into a unique centralized subintensive department to treat COVID-19 patients. The factors that made it possible to adequately face the stress due to patients' hospitalization were human resources and innovative elements to provide oxygen therapy. It is to underline that the logistic and methodological reality was not planned to cope with this emergency.

Tight junction formation in early Xenopus laevis embryos: identification and ultrastructural characterization of junctional crests and junctional vesicles.

How tight junctions (TJ) form during early amphibian embryogenesis is still an open question. We used time-lapse video microscopy, scanning electron microscopy (SEM), TEM and freeze-fracture to gain new insight into TJ biogenesis in early clevages of Xenopus laevis. Video analysis suggests three phases in junction formation between blastomeres. A first "waiting" phase, where new unpigmented lateral membranes are generated. A second "mixing" phase, where the unpigmented lateral membrane is separated from the pigmented apical membrane by an area showing a limited degree of intermingling of cortical pigment. And a third "sealing" phase, characterized by the formation of cingulin-containing boundaries between membrane domains, and their rapid directional adhesion in a zipper-like fashion. By SEM, we characterized these boundaries ("junctional crests", JC) as arrays of villiform protrusions at the border between old and new membranes. In the 2-cell embryo, JC are deeply located, and thus not visible at the surface, but they become increasingly more superficial as cleavages progress. After adjacent blastomeres have adhered to each other, fractured JC display linear arrays of junctional vesicles (JV) of 1-3 mum diameter. TEM analysis shows that JV are symmetrically located near the apposed membranes of adjacent blastomeres, and that the membranes near the JV display focal sites of intimate contact, typical of TJ. Freeze-fracture analysis confirms that intramembrane fibrils, typical of TJ, are present at adhesion sites. We conclude that TJ are formed following the sealing of JC, through the recruitment, sorting and assembly of membrane and cytoplasmic proteins at or near JV.