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Scientists are using human stem cells to create a structure that mimics a pre-embryo and can serve as a research alternative to a real one. They say these “blastoids” provide an efficient, ethical way to study human development and pursue biomedical discoveries in fertility and contraception. The latest effort was detailed Thursday in the journal Nature. The structures aren’t embryos, but scientists nevertheless didn’t let them grow past two weeks in deference to longstanding ethical guidelines. (Ungar, 12/2)

The stem cells were no more than a week old when scientists moved them from their slick-walled plastic wells into ones lined with a thin layer of human endometrial tissue. But in that time, the cells had multiplied and transformed, organizing themselves into semi-hollow spheres. Per the instructions of the chemical cocktail in which they’d been steeping, they were trying to turn into embryos. Video cameras captured what happened next: The balls of cells rotated until they were cavity-side-up, before finally touching down and grabbing onto the endometrial layer, a cellular proxy for a human uterus. Days later, when the scientists dipped paper test strips into the wells, pink lines appeared. Their Petri dishes were pregnant. (Molteni, 12/2)

“Social distancing” quickly became part of the lexicon when the coronavirus pandemic began two years ago. The World Health Organization defined it as staying 3 feet away from one another. The Centers for Disease Control and Prevention doubled that. Nearly overnight, footprint decals appeared on store floors, spaced 6 feet apart. Memes and jokes popped up online, many from introverts who cheered staying away from other people. (Clanton, 12/2)

The neutralizing monoclonal antibody lenzilumab significantly raised survival without the use of mechanical ventilation in hospitalized COVID-19 patients and had a good safety profile, according to a phase 3 clinical trial yesterday in The Lancet Respiratory Medicine. A team led by Mayo Clinic researchers enrolled 520 hospitalized COVID-19 pneumonia patients from 29 sites in the United States and Brazil from May 5, 2020, to Jan 27, 2021; 479 patients were included in a modified intention-to-treat population. Participants were randomly assigned in a 1:1 ratio to receive either three intravenous 600-milligram (mg) doses of lenzilumab or a placebo given 8 hours apart. (12/2)

The origins of the coronavirus are still not clear, but a University of South Florida professor says the evidence -- and history -- would suggest it came from an animal. Sean Doody is a biologist who tracks the spread of viruses and diseases in wildlife. Health News Florida's Leda Alvim spoke with Doody about the role animal trafficking plays in the transmission of viruses and how we might prevent future pandemics. (Alvim, 12/2)

Two new drugs are awaiting authorization from the Food and Drug Administration for treating patients with COVID-19, and both may be effective against the omicron variant. One is made by Merck, the other by Pfizer. The Merck drug has been in development for years. When the pandemic began, Pfizer's drug didn't exist. The story of its development is another example of how COVID-19 has sped up the drug and vaccine development process. (Palca, 12/3)

Bayer (BAYGn.DE) said a combination therapy including its Nubeqa drug was shown to prolong the lives of men suffering from metastatic prostate cancer in a clinical study, underpinning the company's hopes for the drug to become a key sales driver. Nubeqa, also known as darolutamide, improved overall survival in a combination with standard care when compared to standard care alone, which was the primary goal of the trial, the German company said in a statement on Friday. (Burger, 12/3)

Lead, mercury and other pollutants could be affecting the ratio of boys to girls born each year, according to a study published Thursday in the peer-reviewed journal PLOS Computational Biology. The analysis, which reviewed data from about half of the U.S. population and everyone in Sweden, suggested common pollutants are affecting children before they’re born and having similar effects across large groups of people and on separate continents. (Bush, 12/2)