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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

2:03 p.m. ET

Sen. Claire McCaskill (D-Mo.) held nothing back while grilling President-elect Donald Trump's treasury secretary nominee, Steven Mnuchin, on Thursday. McCaskill used the entirety of her time to press Mnuchin on the issue of Trump's potential conflicts of interest due to his global business, wondering aloud if Trump would fire the government ethics officer in order to install someone more favorable to his organization's interests.

At one point during the questioning, McCaskill asked: "Do you agree your boss is famous for firing people?"

Mnuchin, cornered, admitted: "Well, he has a show about it."

McCaskill continued, asking Mnuchin, "Isn't it true that a lot of [Trump's] debt is held by foreign interests?" Mnuchin deflected: "I don't know, I've just read it in the papers."

"Do you think you should know that, as someone who runs the committee on foreign investments, if we're talking about the commander-in-chief?" McCaskill pressed.

Mnuchin mostly agreed: "I think you have a valid point," he said. Jeva Lange

1:36 p.m. ET

Energy secretary nominee and former Gov. Rick Perry (R-Texas) deferred to scientists when asked Thursday during his Senate confirmation hearing if he would support the longstanding ban on nuclear testing. "I'm going to rely upon their observations of whether there is clear technical ability to use the technology that we have today," Perry said, referring to Department of Energy scientists and private-sector scientists. "I think anyone would be of the opinion that if we don't ever have to test another nuclear weapon, that would be a good thing — not just for the United States, but for the world."

Perry's answer came after some chiding from Sen. Bernie Sanders (I-Vt.), who asked the question because of President-elect Donald Trump's interest in allowing more countries to get nuclear weapons, and the fact that "more than 60 percent" of the Energy Department's budget deals with nuclear energy. Initially, Perry answered the question by pointing to the importance of the U.S. having "a nuclear arsenal that is modern, that is safe." "The question," Sanders said, cutting in, was about "nuclear testing."

Perry was similarly circumspect about whether he would support the storage of nuclear waste at Nevada's Yucca Mountain, a site the U.S. government had once eyed for dumping nuclear waste. Trump's administration has reportedly discussed reviving that plan. "I will not sit here in front of you and tell you absolutely no way is Nevada going to be the recipient of high-level waste," Perry said. Becca Stanek

1:22 p.m. ET

During his Senate confirmation hearing Thursday as President-elect Donald Trump's energy secretary nominee, former Gov. Rick Perry (R-Texas) faced tough questions from Sen. Al Franken (D-Minn.) on his stance on climate change, whether he'd fight for the Energy Department against potential budget cuts from the Trump administration, and his views on maintaining the Iran nuclear deal.

But before that, he made an unfortunate double entendre in greeting Franken, who was seated at the dais:

Oops! Kimberly Alters

1:14 p.m. ET

President-elect Donald Trump's tax plan has been criticized by some analysts for possibly adding "trillions" to the national debt and significantly benefiting high-income households. When pressed on the issue during his Senate confirmation hearing, Trump's treasury secretary nominee, Steven Mnuchin, seemed to admit that the plan was less than ideal:

"I think, as you know, we had a rather modest campaign staff relative to the other people out there," Mnuchin said. "One of the things I look forward to if I'm confirmed is having access to all the people at the Treasury who are able to model these things." Watch below. Jeva Lange

1:00 p.m. ET

After an emotional farewell speech and warm final press conference, President Barack Obama on Thursday took one more opportunity to thank the American people just one day before he leaves office. In a long-standing White House tradition, the outgoing president leaves his successor a personal note in the Oval Office containing words of wisdom based on what they've learned during their tenure — but, as Obama explained in a letter to the public, he wanted to go a step further.

"Before I leave my note for our 45th president, I wanted to say one final thank you for the honor of serving as your 44th," the president wrote. "Because all that I've learned in my time in office, I've learned from you."

The note goes on to offer Americans hope "when the arc of progress seems slow," an apparent nod to those feeling apprehensive about the incoming administration. Read the president's full parting message below. Kelly Gonsalves

12:28 p.m. ET
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President-elect Donald Trump's administration is reportedly planning massive cuts to the Energy Department's budget, and former Gov. Rick Perry (R-Texas), Trump's nominee for energy secretary, was faced with the tough question of how he'd push back at his Senate confirmation hearing Thursday. Sen. Angus King (I-Maine) asked for Perry's commitment to fight for the department's research budget, telling Perry that Trump's administration would be "cutting the legs out from under you" if they made the "devastating" and "absolutely nuts" budget cuts.

Perry cited his "rather interesting background" of "defending budgets," but didn't exactly commit one way or the other. In fact, all Perry said in response to King's question was that he knows "what the Department of Energy should be good at." Earlier in the hearing, Perry joked that maybe Trump's team would "forget" the cuts they'd proposed.

Per The Hill's report, Trump's team is reportedly planning to slash funding "for nuclear physics and advanced scientific computing research to 2008 levels, eliminate the Office of Electricity, eliminate the Office of Energy Efficiency and Renewable Energy, and scrap the Office of Fossil Energy, which focuses on technologies to reduce carbon dioxide emissions." Becca Stanek

12:23 p.m. ET
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President-elect Donald Trump's transition team has prepared a drastic plan to cut the federal budget, The Hill reports. The planned changes reportedly aim to shrink federal spending by $10.5 trillion over 10 years.

Among the budget-slashing proposals are reducing funding for the Commerce and Energy departments, including eliminating certain programs altogether; imposing significant budget cuts on the departments of State, Transportation, and Justice; privatizing the Corporation for Public Broadcasting, which distributes funding to nearly 1,500 locally owned public radio and TV stations; and eliminating the National Endowment for the Arts and National Endowment for the Humanities, which disperses grants to cultural institutions and humanities programs.

As The Hill notes, the Trump team's proposed budget aligns closely with a budget proposal published last year by the conservative Heritage Foundation, and resembles past outlines that have been supported by congressional Republicans. It is as yet unclear whether the transition team's proposed budget would address Social Security and Medicare, which contribute largely to the federal deficit.

The budget proposal — which The Hill calls the "skinny budget" — should be released within 45 days of Trump taking office. Read more about the incoming administration's budget ideas at The Hill. Kimberly Alters

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