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May 4, 2014
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Two studies published on Sunday show that blood from young mice reversed aging in old mice, rejuvenating both their muscles and their brains, The New York Times reports.

Dr. Saul Villeda at the University of California, San Francisco, and his colleagues discovered that after young mice and old mice were stitched together at their flanks and their blood was flowing through each other, the old mice formed several new neurons in the hippocampus region of the brain, an important area for imprinting memories. The scientists also removed cells and platelets from the blood of young mice and injected the remaining plasma into old mice, which helped the older rodents perform better on memory tests.

Over at Harvard University, Dr. Amy J. Wagers and her team found that when old mice were joined together with young mice, more blood vessels grew in the brain of the old mice, leading to the creation of more neurons that gave the old mice a better sense of smell. During an earlier study, Wagers and her colleagues had discovered that GDF11, a protein, was plentiful in young mice and scarce in old mice, and could rejuvenate heart tissue when injected into older mice.

This time around, Wagers and her colleagues injected GDF11 into the old mice (not joined to younger mice) and found that it also spurred the growth of blood vessels and neurons in the brain, as well as — in a separate new study — stem cells in the aging muscles, increasing the strength and endurance of older mice.

Taken together, the separate research could eventually lead to treatments for human heart disease and degenerative brain disorders like Alzheimer's, among other Fountain of Youth remedies. "There's no conflict between the groups, which is heartening," Dr. Richard M. Ransohoff, director of the Neuroinflammation Research Center at the Cleveland Clinic, told The New York Times.

The idea of being able to rejuvenate body parts this way is exciting, but scientists also warn that stem cells could multiply uncontrollably, leading to cancer. Villeda's team published its findings in the journal Nature Medicine, while Wagers' studies came out in Science. Catherine Garcia

February 13, 2016
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Donald Trump is backed into a corner in South Carolina, where he has been routinely booed by the debate audience for everything from insulting Jeb Bush to insinuating 9/11 was George W. Bush's fault. Perhaps as a result, when Ted Cruz turned his criticism on Trump, Trump came back swinging with a particular vengeance.

"You are the single biggest liar, you're probably worse than Jeb Bush," Trump said — a mighty insult in his book. Trump added that Cruz is a "nasty guy."

"This guy lied about Ben Carson…and he just continues," Trump went on.

However, Trump was met with what is becoming a familiar sound this Saturday: Boos. Watch below. Jeva Lange

February 13, 2016
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Marco Rubio and Ted Cruz are the only Cuban-Americans on the South Carolina Republican debate stage, and things got especially heated and personal when Cruz criticized a time Rubio went on Univision to speak in Spanish about his immigration policy.

When Rubio was given the chance to respond, he snapped, "I don't know how [Cruz] knows what I said on Univision because he doesn't speak Spanish."

Cruz countered by shouting in Spanish at Rubio. "We can do this in Spanish, if you want," he roughly said.

Some Spanish speakers took issue with Cruz's reply, however:

Nevertheless, Rubio didn't take Cruz up on the challenge, continuing on in English — but it was a moment for the books. Watch below. Jeva Lange

February 13, 2016

Jeb Bush and Donald Trump locked horns for the second time in the South Carolina Republican debate when Trump took a swing at one of his favorite subjects of ridicule — the Bush family.

"I am sick and tired of him going after my family," Bush began in response, going on to say that, "While Donald Trump was building a reality TV show, my brother was building a security apparatus to keep us safe."

Trump interrupted, pointing out that 9/11 happened while George W. Bush was in office — and was greeted with a round of angry boos.

"He had the gall to go after my mother," Bush went on. "My mom is the strongest person I know."

But Trump, never one to cede the last word, quipped, "She should be running." Jeva Lange

February 13, 2016
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After Jeb Bush explained his policy for going after ISIS at the GOP presidential debate in South Carolina Saturday night, Donald Trump ripped into the former Florida governor — and was met with ferocious boos from the audience. "Jeb is so wrong, Jeb is absolutely so wrong," Trump said of Bush's call to dispose of Syrian President Bashar al-Assad, only to get the audience hissing.

Trump wasn't put off. "You know who that is? That's Jeb's special interest and lobby talking," he said, drawing his second round of boos.

"I only tell the truth, lobbyists," Trump replied. Jeva Lange

February 13, 2016
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The opening questions of the CBS Republican debate naturally surrounded the death of Justice Antonin Scalia, with Donald Trump being the first up to bat. Responding to the question of appointing Justice Scalia's replacement, Trump said he believed Obama would pick a successor within the remaining 11 months of his presidency— and if Trump were in the president's shoes, he would do the same.

Nevertheless, Trump had some advice to those interested in protecting Scalia's legacy of conservatism: "Delay, delay, delay." Watch below. Jeva Lange

February 13, 2016
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Supreme Court Justice Antonin Scalia, who died Saturday at the age of 79, had a way with words. In court, those words weren't so much spoken as thundered. And in his memorable dissents or important majority decisions, those words could often be described as biting.

The Catholic, Italian-American justice, the longest-serving on the court, was passionate about his belief in the Constitution and his faith.

"He was a hysteric in cases he cared about most," legal scholar Cass Sunstein told NPR. The cases that fired him up ranged from same-sex marriage and prayer in public school, to the death penalty and ObamaCare.

Scalia so intensely disagreed with the court's 2015 decision to uphold the Affordable Care Act ruling that he voiced his colorful dissent aloud from the bench, with phrases like "jiggery-pokery," "quite absurd," "feeble arguments," and "pure applesauce."

Words were important to Scalia, both in his reading of the Constitution ("The Constitution that I interpret and apply is not living but dead, or as I prefer to call it, enduring.") and in his "carefully crafted" opinions, which will live on long after his death.

Read more about Antonin Scalia's life, career, and legacy at NPR. Lauren Hansen

February 13, 2016
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Following the unexpected death of conservative Supreme Court Justice Antonin Scalia on Saturday, Republicans and Democrats immediately began fighting over who should select his replacement. Senate Majority Leader Mitch McConnell (R-Ky.) said in a statement that "this vacancy should not be filled until we have a new president," while Senate Minority Leader Harry Reid (D-Nev.) said President Obama "can and should send the Senate a nominee right away."

Were Obama to nominate Scalia's replacement, it would dramatically refashion the ideological make-up of the court, with the reliably conservative Scalia almost certainly being replaced by a liberal like Obama's other two nominees, Elena Kagan and Sonia Sotomayor. Ben Frumin

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