Anyone who has ever seriously tried to lose weight knows the real challenge is not shedding the pounds but keeping them off. Mammals are evolutionarily programmed to respond to weight loss by bouncing back—probably a resilience mechanism geared to help us survive nutritional uncertainty and the stress of feast-and-famine cycles. Now endocrinologists at Xiangya Hospital and Central South University in Hunan, China, have discovered a possible way around this fickle biology. They found that specific white blood cells called CD7+ monocytes accumulate in mouse and human bone marrow during weight loss, where they secrete proteins that activate signaling mechanisms in the body to keep the weight off. The cells grow quiet over time, however, and the weight comes back. They showed that giving mice a protein called FMS-like tyrosine kinase 3 ligand (FLT3L) keeps the CD7+ cells active and prevents rapid weight regain, suggesting a possible future hack. Cell Metabolism
How transformative would it be if much of the world switched diets to include large increases in plant-derived protein? Quite a bit, according to researchers at the International Institute for Applied Systems Analysis in Laxenburg, Austria. Modeling the effect of substituting half of all pork, chicken, beef, and milk (the main agricultural animal products) by 2050, they found such a shift would halt deforestation, increase available land, lower greenhouse gas emissions by almost a third (and even more if reclaimed farmland is rewilded), and lower undernourishment worldwide. Nature Communications
Accelerated approval brings drugs to market sooner and was put in place by the U.S. Food and Drug Administration in 1988 in response to AIDS protests demanding more rapid access to antiretroviral drugs. In the 35 years since, however, it has been used more for cancer drugs than anything else. That’s because one of its key features is that it embraces “surrogate” end points—biological measures of the drug’s effect, like shrinking tumors, rather than more clinical ones, like saving lives. Surrogate end points are attractive to drug companies because they allow clinical trials to proceed rapidly, enroll fewer patients, and bring potentially lucrative cancer drugs to the market faster and at lower cost. The program has problems, however, and according to doctors from Queen’s University in Ontario, Harvard University, and Yale University, it can lead to “exceptionally” high drug prices and so-called “dangling” approvals where a drug remains on the market for years even after later clinical trials fail to show its effectiveness. NEJM
Researchers at Shanghai Jiao Tong University in China have developed general-purpose integrated circuits using DNA in liquid. Integrated circuits, like the familiar silicon chips found in our phones and computers, combine transistors and other electronic components to form the basis for computing. The idea of using liquid-phase DNA for integrated circuits is attractive because you can place lots of different DNA molecules in a single test tube and conduct massively parallel computations. DNA is also the natural “stuff” of biology, which makes it intrinsically compatible for applications like disease detection in biological samples. The researchers demonstrated this potential by designing a system of 500 strands of DNA that made up about 30 DNA-based programmable logic gates. As a proof-of-principle, they showed they could correctly solve the loathsome quadratic equation. Nature
Chronic obstructive pulmonary disease (COPD) is a progressive condition brought on by smoking and other causes that affects some 16 million Americans. It’s typically treated with bronchodilators, which can expand airways in the lungs to make breathing easier but do nothing to regenerate lost or damaged lung tissue. A small phase 1 clinical trial involving 20 people with COPD tested the safety and efficacy of a new form of treatment involving regenerating the inner “epithelial” lining of the lungs by transplanting adult lung stem cells (known as P63+ lung progenitor cells). The trial followed 17 people who received the transplants and three controls who received a sham treatment for 24 weeks. The work, which was presented this week at the European Respiratory Society International Congress, showed the treatment to be promising. It was safe and led to significant improvements on standard tests of pulmonary function and quality of life. Abstract OA4297
Comparing the brains of 13 species of primates, including humans, great apes, and monkeys, anthropologists at Kent State University in Ohio have concluded that the human brain is unique in having the highest density of neurons that use a neurotransmitter called neuropeptide Y inside the nucleus accumbens, a brain region central for motivation and reward-driven action. This is significant, they say, because that high density in that reptile-like brain region pushes us to seek more fat and sugar in our diets, puts us at higher risk for obesity, leads to eating disorders, and contributes fundamentally to our propensity for drug and alcohol addiction. The distinct neurological traits appear to have emerged in ancient humans more than a million years ago, and may have contributed both to the expansion of the human brain’s cortical regions and our enhanced cognitive ability in the millennia since. But at what cost? “We are thus essentially wired for hedonic eating and addictive behaviors,” the researchers write. PNAS
Who knew a vegan diet could be so controversial? Apparently it is when fed to cats. The pet food industry is large, worth hundreds of billions of dollars a year in sales, and rapidly growing. One important segment of this industry markets healthier and more environmentally friendly alternatives to meat, finding alternative sources of protein for pets in things like plants, insects, fungi, and seaweed. But some experts are profoundly against the idea. A professional association of British veterinarians issued a statement in 2020 pointing out that cats are obligate carnivores and have to eat meat. One expert has gone so far as to state publicly that people in Britain who feed their cats vegan diets may actually be committing crimes under the U.K.’s Animal Welfare Act. Into this fray comes a new study from the Center for Animal Welfare at the University of Winchester in England, which polled 1,369 cat owners, about 10 percent of whom fed their cats vegan diets. Asking the owners to self-report on their cats’ health, the study found cats fed vegan diets tended to be healthier. But we wonder: What do the cats think? PLOS One
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