Background The question of an optimal strategy and outcomes in COVID-19 tracheostomy has not been answered yet. The critical focus in our case study is to evaluate the outcomes of tracheostomy on intubated COVID-19 patients. Methods A multicentric prospective observational study of 1890 COVID-19 patients undergoing tracheostomy across 120 hospitals was conducted over 7 weeks in Spain (March 28 to May 15, 2020). Data were collected with an innovative approach: instant messaging via WhatsApp. Outcome measurements: complications, achieved weaning and decannulation and survival. Results We performed 1,461 surgical (81.3%) and 429 percutaneous tracheostomies. Median timing of tracheostomy was 12 days (4-42 days) since orotracheal intubation. A close follow-up of 1616/1890 (85.5%) patients at the cutoff time of 1-month follow-up showed that in 842 (52.1%) patients, weaning was achieved, while 391 (24.2%) were still under mechanical ventilation and 383 (23.7%) patients had died from COVID-19. Decannulation among those in whom weaning was successful (n = 842) was achieved in 683 (81%) patients. Conclusion To the best of our knowledge, this is the largest cohort of COVID-19 patients undergoing tracheostomy. The critical focus is the unprecedented amount of tracheostomies: 1890 in 7 weeks. Weaning could be achieved in over half of the patients with follow-up. Almost one out of four tracheotomized patients died from COVID-19.

Chromatin structure imposed by condensin II at centromeres enables xHJURP-mediated incorporation of CENP-A.

Tumour formation is blocked by two barriers, replicative senescence and crisis1. Senescence is triggered by short telomeres and is bypassed by disruption of tumour suppressive pathways. After senescence bypass, cells undergo crisis, during which almost all of the cells in the population die. Cells that escape crisis harbor unstable genomes and other parameters of transformation. The mechanism of cell death during crisis remained elusive. We show that cells in crisis undergo spontaneous mitotic arrest, resulting in death during mitosis or in the following cell cycle. The phenotype was induced by loss of p53 function, and suppressed by telomerase overexpression. Telomere fusions triggered mitotic arrest in p53-compromised non-crisis cells, indicating such fusions as the underlying cause. Exacerbation of mitotic telomere deprotection by partial TRF2 knockdown2 increased the ratio of cells that died during mitotic arrest and sensitized cancer cells to mitotic poisons. We propose a crisis pathway wherein chromosome fusions induce mitotic arrest, resulting in mitotic telomere deprotection and cell death, thereby eliminating precancerous cells from the population.

Telomere length maintenance ensures self-renewal of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), however the mechanisms governing telomere length homeostasis in these cell types are unclear. Here, we report that telomere length is determined by the balance between telomere elongation mediated by telomerase and telomere trimming, controlled by the homologous recombination proteins XRCC3 and Nbs1 that generate single-stranded C-rich telomeric DNA and double-stranded telomeric circular DNA (T-circles), respectively. We found that reprogramming of differentiated cells induces T-circle and single stranded C-rich telomeric DNA accumulation, indicating the activation of telomere trimming pathways that compensate telomerase dependent telomere elongation in hiPSCs. Excessive telomere elongation compromises telomere stability and promotes the formation of partially single-stranded telomeric DNA circles (C-circles) in hESCs, suggesting heightened sensitivity of stem cells to replication stress at overly long telomeres. Thus, tight control of telomere length homeostasis is essential to maintain telomere stability in hESCs.

PIK3R2 encodes a ubiquitous regulatory subunit (p85β) of PI3K, an enzyme that generates 3-polyphosphoinositides at the plasma membrane. PI3K activation triggers cell survival and migration. We found that p85β expression is elevated in breast and colon carcinomas and that its increased expression correlates with PI3K pathway activation and tumor progression. p85β expression induced moderate PIP 3 generation at the cell membrane and enhanced cell invasion. In accordance, genetic alteration of pik3r2 expression levels modulated tumor progression in vivo. Increased p85β expression thus represents a cellular strategy in cancer progression.A ctivation of class I PI3K is involved in the pathogenesis of cancer. PI3Ks are lipid kinases that phosphorylate membrane phosphoinositides [i.e., phosphatidylinositol (PtdIns)] to generate PtdIns(3,4)P 2 (PIP 2 ) and PtdIns(3,4,5)P 3 (PIP 3 ). PI3K is composed of a regulatory and a p110 catalytic subunit. Four genes encode the highly conserved p110 catalytic subunit (PIK3CA, CB, CD, and CG). p110α, β, and δ associate with p85 regulatory subunits and are activated mainly by growth factor receptors; p110γ associates with distinct regulatory subunits and is activated preferentially by G protein-coupled receptors (1-3). Three genes encode p85-type regulatory subunits: PIK3R1 (p85α, p55α, p50α), PIK3R2 (p85β), and PIK3R3 (p55γ). R1 and R2 are ubiquitously expressed and R3 expression is tissue-restricted (4).p85β is expressed at lower levels than p85α in most tissues (5-7). Whereas mice deficient in Pik3r2 develop normally and exhibit only moderate metabolic and immunological defects (7) Pik3r1 −/− mice die perinatally (8). p85α controls p110 stability and blocks p110 activity during quiescence (9). The inhibitory role of p85α on p110 activity explains why WT PIK3R1 expression is normally reduced in tumors, and that p85α mutations that relieve p110 from p85 inhibition have been found in cancer (10). Despite extensive analysis of p85α mutations in tumors (10-12), p85β involvement in cancer is less well studied. Here we analyzed the potential contribution of p85β in cancer.Results p85β Expression Is Increased in Breast and Colon Carcinomas. By using microarray technology, we performed a preliminary survey of the expression of the genes that form part of the PI3K pathway in a collection of clinical breast (n = 14) and colon carcinomas (n = 12). Comparison of PI3K subunit expression showed that mRNA levels of PIK3R2 (which encodes p85β) were increased in nearly half the carcinoma samples examined, whereas PIK3R1 (which encodes p85α) was decreased (Fig. S1). To study this finding in more detail, we compared 20 colon adenocarcinomas (CCs) and 35 breast carcinomas (BCs) with normal surrounding tissue. Tumor and normal samples had comparable numbers of epithelial cells, and normal tissue had a low percentage of malignant cells (0-10%).To evaluate p85β expression levels, we prepared extracts from normal and tumor samples and analyzed p85 levels by Western blot (WB). We generated anti-p85β Abs an...