上海419最新论坛

Zika’s damaging neurological effects might someday be enlisted for good — to treat brain cancer.

In human cells and in mice, the virus infected and killed the stem cells that become a glioblastoma, an aggressive brain tumor, but left healthy brain cells alone. Jeremy Rich, a regenerative medicine scientist at the University of California, San Diego, and colleagues report the findings online September 5 in the Journal of Experimental Medicine.

Previous studies had shown that Zika kills stem cells that generate nerve cells in developing brains (SN: 4/2/16, p. 26). Because of similarities between those neural precursor cells and stem cells that turn into glioblastomas, Rich’s team suspected the virus might also target the cells that cause the notoriously deadly type of cancer. In the United States, about 12,000 people are expected to be diagnosed with glioblastoma in 2017. (It’s the type of cancer U.S. Senator John McCain was found to have in July.) Even with treatment, most patients live only about a year after diagnosis, and tumors frequently recur.
In cultures of human cells, Zika infected glioblastoma stem cells and halted their growth, Rich and colleagues report. The virus also infected full-blown glioblastoma cells but at a lower rate, and didn’t infect normal brain tissues. Zika-infected mice with glioblastoma either saw their tumors shrink or their tumor growth slow compared with uninfected mice. The virus-infected mice lived longer, too. In one trial, almost half of the mice survived more than six weeks after being infected with Zika, while all of the uninfected mice died within two weeks of receiving a placebo.

Using a virus to knock out cancer isn’t a completely new idea. Treatments that rely on modified polioviruses to target tumors such as glioblastomas are already in clinical trials in the United States, and there’s a modified herpesvirus approved by the U.S. Food and Drug Administration for treating melanoma.

These cancer-fighting viruses seem to work in two ways, says Andrew Zloza, head of surgical oncology research at the Rutgers Cancer Institute of New Jersey in New Brunswick. First, the viruses infect and kill cancer cells. Then, as those cancer cells split open, previously hidden tumor fragments become visible to the immune system, which can recognize and fight them.

“Right now we don’t know what kind of viruses are best” for fighting cancer, Zloza says — whether it’s more effective to use a common virus that many people have been exposed to or something more unusual. But now, Zika is yet another candidate.

Further testing is needed to determine whether the virus is safe and effective in humans. Since Zika’s effects are more harmful in developing brains, a Zika-based cancer therapy might be safe only in adults. And the virus would need to be genetically modified to make it safer and less transmissible.
Rich and colleagues are now testing in mice whether combining Zika with traditional cancer treatments such as chemotherapy is more effective than either treatment by itself. Because Zika targets the cells that generate tumor cells, it might prevent tumors from recurring.

Around the six-month mark, babies start to get really fun. They’re not walking or talking, but they are probably babbling, grabbing and gumming, and teaching us about their likes and dislikes. I remember this as the time when my girls’ personalities really started making themselves known, which, really, is one of the best parts of raising a kid. After months of staring at those beautiful, bald heads, you start to get a glimpse of what’s going on inside them.

When it comes to learning language, it turns out that a lot has already happened inside those baby domes by age 6 months. A new study finds that babies this age understand quite a bit about words — in particular, the relationships between nouns.
Work in toddlers, and even adults, reveals that people can struggle with word meanings under difficult circumstances. We might briefly falter with “shoe” when an image of a shoe is shown next to a boot, for instance, but not when the shoe appears next to a hat. But researchers wanted to know how early these sorts of word relationships form.

Psychologists Elika Bergelson of Duke University and Richard Aslin, formerly of the University of Rochester in New York and now at Haskins Laboratories in New Haven, Conn., put 51 6-month-olds to a similar test. Outfitted with eye-tracking gear, the babies sat on a parent’s lap and looked at a video screen that showed pairs of common objects. Sometimes the images were closely related: mouth and nose, for instance, or bottle and spoon. Other pairs were unrelated: blanket and dog, or juice and car.

When both objects were on the screen, the parents would say a sentence using one of the words: “Where is the nose?” for instance. If babies spent more time looking at the nose than the other object, researchers inferred that the babies had a good handle on that word.

When the babies were shown tricky pairs of closely related objects, like a cup of juice and a cup of milk, the babies spent nearly equal time looking at both pictures, no matter what word their parents said. But when the images were really distinct (juice and car, for instance) the babies spent more time looking at the spoken word.
These babies detected a difference between the “milk-juice” pair and the “juice-car” pair, recognizing that one pair is similar and the other isn’t, the researchers conclude November 20 in the Proceedings of the National Academy of Sciences.
To see whether this ability was tied to domestic life, the researchers sent the babies home with specialized gear: vests with audio recorders and adorable hats outfitted with small video cameras, one just above each ear. A camera on a tripod in a corner of the home also captured snippets of daily life. The resulting video and audio recordings revealed that babies whose caregivers used more nouns for objects in the room were better at the word task in the lab.

That means that babies learn words well when they can actually see the object being talked about. Hearing, “Open your mouth. Here comes the spoon!” as they watch the spoon come flying toward their face makes a bigger vocabulary impression than “Did you like riding in the car yesterday?”

A similar idea came from a recent study on preschoolers. These kids learned best when they saw one picture at a time (or when parents pointed at the relevant object). Babies — and older kids, too — like to see what you’re talking about.

The results are too early to provide advice to parents, says Bergelson, a cognitive and developmental psychologist. “But I think one thing suggested by our work is that parents should consider their young baby to be a real conversational partner,” she says. “Even young infants are listening and learning about words and the world around them before they start talking themselves, and their caregivers make that possible.”

There’s still lots to figure out about how babies soak up vocabulary. And as scientists come up with more ways to peer into the mysterious inner workings of a baby’s mind, those answers might lead to even more interesting conversations with our babies.

PHILADELPHIA — If you want to beat them, join them. Some breast cancer tumors may follow that strategy to spread through the body.

Breast cancer tumors can fuse with blood vessel cells, allowing clumps of cancer cells to break away from the main tumor and ride the bloodstream to other locations in the body, suggests preliminary research. Cell biologist Vanesa Silvestri of Johns Hopkins University School of Medicine presented the early work December 4 at the American Society for Cell Biology/European Molecular Biology Organization meeting.

Previous research has shown that cancer cells traveling in clusters have a better chance of spreading than loners do (SN: 1/10/15, p. 9). But how clusters of cells get into the bloodstream in the first place has been a mystery, in part because scientists couldn’t easily see inside tumors to find out.

So Silvestri and colleagues devised a see-through synthetic version of a blood vessel. The vessel ran through a transparent gel studded with tiny breast cancer tumors. A camera attached to a microscope allowed the researchers to record the tumors invading the artificial blood vessel. Sometimes the tumors pinched the blood vessel, eventually sealing it off. But in at least one case, a small tumor merged with the cells lining the faux blood vessel. Then tiny clumps of cancer cells broke away from the tumor and floated away in the fluid flowing through the capillary. More work is needed to confirm that the same process happens in the body, Silvestri said.

A new analysis is shedding light on drought in Mongolia, both past and future.

By studying the rings of semifossilized trees, researchers constructed a climate history for the semiarid Asian nation spanning the last 2,060 years — going 1,000 years further back than previous studies.

It was suspected that a harsh drought from about 2000 to 2010 that killed tens of thousands of livestock was unprecedented in the region’s history and primarily the result of human-caused climate change. But the tree ring data show that the dry spell, while rare in its severity, was not outside the realm of natural climate variability, researchers report online March 14 in Science Advances.
“This is a part of the world where we don’t know about the past climate,” says Park Williams, a bioclimatologist at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y., who was not involved with the study. “Having this record is a great resource for trying to understand past droughts in the region.”

In recent years, many studies have sought to unsnarl the role of anthropogenic climate change from natural variability on extreme weather events (SN: 1/20/18, p. 6). Such work is necessary for more accurately predicting future climate trends and helping governments prepare for the most severe scenarios, says study coauthor Amy Hessl, a physical geographer at West Virginia University in Morgantown. This is especially true in countries like Mongolia that lack certain infrastructure, such as enough water reservoirs, to ease the impact of events like prolonged drought.

Hessl and her colleagues studied tree rings in hundreds of samples of Siberian pines, well-preserved by Mongolia’s naturally dry climate. A ring’s width indicates how much the tree grew in a year. In wet years, the rings are wider; in dry years, skinnier.
The recent dry spell was the severest in recorded history. But the rings showed that an even more severe drought took place around the year 800, long before anthropogenic climate change began.

Still, computer simulations suggest that about a third of the recent drought’s severity could have been caused by elevated temperatures linked to climate change, the researchers found. The finding is consistent with studies on how climate change has affected other recent droughts in South Africa and California.

Using computer simulations, Hessl and her colleagues conclude that droughts in coming decades may not be any worse than those seen in Mongolia’s past. The team predicts that as global temperatures rise over the next century, Mongolia will first become drier, then wetter. Increased heat initially will dry out the plains. But at a certain point, hot air holds more moisture, leading to increased precipitation.

Those climate patterns will likely guide how Mongolia develops, Hessl says, because they have in the past. In 2014, she and colleagues published a paper detailing how a 15-year period of unprecedented temperate and rainy conditions in 13th century Mongolia may have led to the rise of Genghis Khan (SN Online: 3/10/14).