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Entries in Lab Mice (2)

Wednesday
Jul252012

Deaf, Blind Mice Get High-Tech Cures

Comstock/Thinkstock(BERKELEY, Calif.) -- It's an exciting day for deaf, blind mice. Scientists are reporting success with treatments that seem to restore sight and hearing in mice born without those senses. The treatments have a long way to go before the researchers will know if they can help humans, but the early results are encouraging.

Scientists from the University of California, Berkeley studied mice with blindness similar to the inherited and age-related blindness that affects humans. When a person or mouse goes blind, the cells in the retina of the eye that respond to light, known as rods and cones, die off, leaving the eye without the ability to detect light. The team used a chemical, called AAQ, to target the remaining living cells, which normally aren't activated by light.

When AAQ is struck with light, it turns those non-sensitive cells into light-sensing signal senders for the brain's vision circuitry.

"The first drug candidate or prototype that directly restores photosensitivity," said Richard Kramer, one of the study's authors. "With a drug, you can adjust its dose, discontinue it, or use in combination with other therapies. And this being a simple chemical, you can use chemistry to make it even better."

But the mice weren't permanently cured. The chemical lasts for a few weeks before the mice need another injection. Dr. Marco Zarbin, chair of ophthalmology and visual science at the New Jersey School of Medicine, who was not affiliated with the study, said if the treatment proved to work in humans, the need for repeated injections isn't a major flaw.

"Injecting something into the eye is something that surgeons do all the time," Zarbin said. "The idea that one would have to periodically repeat the injection is not a deal breaker."

Scientists have been testing many avenues to correct blindness in both mice and men – everything from gene therapy to retina transplants to electronic chips implanted in the retina that stimulate defunct cells. But those methods are invasive and permanent, and none have been proved to restore perfectly normal vision. Kramer said the AAQ chemical he used on his blind mice is a valuable alternative simply because the solution can be stopped at any time if, for example, better treatments came along.

Zarbin agreed, and said the approach also appears to target a majority of the retina's million cells, rather than a few thousand that could be stimulated by an electrical chip.

"That's got to improve a patient's light sensitivity," he said. "I'm as encouraged as I could reasonably hope to be by these findings. But you never really know until you've tried it in a person."

Another team of scientists from the University of California, San Francisco, set out to help hearing-impaired mice.

The scientists used gene therapy to correct defects in tiny hair cells in the inner ear in mice that were born deaf. By injecting a gene, called VGLUT3, into the inner ears of the mice, the scientists were able to prompt the hair cells to send signals to the brain, restoring the mice's hearing. The effects lasted about nine weeks in newborn mice and at least seven weeks in adult mice. Two mice still had their hearing after one and a half years.

"This is the first time that an inherited, genetic hearing loss has been successfully treated in laboratory mice, and as such represents an important milestone for treating genetic deafness in humans," said study author Lawrence Lustig in a press release.

Zhen-Yi Chen, a hearing researcher at the Massachusetts Eye and Ear Infirmary, said he considers the findings a breakthrough for deaf humans as well.

"Before we really didn't know if this was doable, even in the animal model. Now we know that it is," he said.

But the study's authors were cautious in applying the findings to humans, noting that although the same genetic mutation is tied to hearing loss in mice and humans, the condition may be entirely different in the animals than it is in people.

Chen said if the approach proved effective in humans, it could represent an improvement over current approaches to treating hearing loss – wearable hearing aids and cochlear implants, neither of which restore hearing to normal levels.

Both of the studies were published today in the journal Neuron. Although they may be a giant leap for mousekind, researchers say it will be a while before the therapies can be tested, proven safe and used in people.

Copyright 2012 ABC News Radio

Friday
Mar302012

Keeping Chilly Lab Mice Warm: Key to Better Science?

Comstock/Thinkstock(NEW YORK) -- Joseph Garner imagines how much happier and healthier lab mice would be in a kinder, gentler environment than the stark cages in chilly laboratories -- and how that, in turn, might improve the outcome of research that underlies human medical advances.

In searching for “one thing we could put in every mouse cage in America that would make every mouse better off and would improve the quality of science done with every mouse,” he focused on a simple fact: mice are chronically cold and suffer from thermal stress.

That “one thing” that could be put in every cage is turning out to be shredded paper, which chilly mice use to build toasty, warm nests like the ones that wild mice build, according to a study published Friday in the journal PLoS One.

Given between a fifth and a third of an ounce of crinkly, coarse shredded paper called Enviro-dri, the mice went to work weaving “these beautiful igloos that are just incredible,” said Garner, an associate professor of comparative medicine at Stanford University in California. He conducted the research while at Purdue University in Indiana, with his then-graduate student Brianna Gaskill, now a postdoctoral scientist at Charles River Laboratories in Wilmington, Mass.

Because mice are nocturnal creatures, he said the lab mice were busy during nighttime hours in the lab, “very much like ‘Where the Wild Things Are.’ They’re very naughty at night.”

Garner has devoted much of the last seven years to understanding why 90 percent of compounds that look promising in animals go on to “fail in human trials.” He’s convinced their environment is part of the answer.

A mouse living in captivity is “a little bit like you or I living in a glass house being looked after by Tyrannosaurus rex,” he suggested. And a drafty house at that. That’s pretty close to conditions for mice, whose 98.4 degree body temperature is close to the 98.6 degrees of the lab technicians who tend to them. But air temperatures in research laboratories typically are kept between 68 and 75.2 degrees, putting them in a state of “cold stress.”

Garner is among the few U.S. scientists “really generating good data to support what animals ‘need and want,’ because animals clearly have their own needs,” said Joanne Zurlo, director of science strategy at the Center for Alternatives to Animal Testing at the Johns Hopkins Bloomberg School of Public Health in Baltimore. Without convincing proof that mouse well-being matters to scientific results, she said other scientists likely won’t buy into the idea that they need to make changes after “keeping mice in these conditions for umpteen years.”

The world’s largest breeder of laboratory mice, which has been supplying mice for the research, recognizes the important influence of laboratory conditions.

“The animal’s environment is a crucial factor in research,” said Kathleen Pritchett-Corning, director of research and professional services for Charles River Laboratories. “In research, we can control almost all aspects of an animal’s environment, but we don’t always know what’s best for the animal.”

She said the company has been “testing this material for our own use and have been very pleased with the results thus far.” She also suggested providing lab mice with nesting materials “could be a huge gain in welfare” and that other elements of lab animals’ environment are “ripe for study,” such as light levels, noise, air movement, type of bedding and feed.

“The healthier and more ‘normal’ the animal, the better the science,” said Pritchett-Corning, a veterinarian who has been working with mice for nearly 20 years. “The better the science, the more likely it is to lead to discoveries and advances that affect human health. It doesn’t matter what kind of animal it is, it deserves the best care we can provide.”

Copyright 2012 ABC News Radio







ABC News Radio