Changes in diet have been linked to a reduction of abnormal behaviors in mentally ill people or animals, but a Purdue University study shows that diet might also trigger the onset of mental illness in the first place.
Joseph Garner, an associate professor of animal sciences, fed mice a diet high in sugar and tryptophan that was expected to reduce abnormal hair-pulling. Instead, mice that were already ill worsened their hair-pulling behaviors or started a new self-injurious scratching behavior, and the seemingly healthy mice developed the same abnormal behaviors.
"This strain of mouse is predisposed to being either a scratcher or a hair-puller. Giving them this diet brought out those predispositions," said Garner, whose results were published in the December issue of the journal Nutritional Neuroscience. "They're like genetically at-risk people."
Garner studies trichotillomania, an impulse-control disorder in which people pull out their hair. The disorder, which disproportionately occurs in women, is thought to affect between 2 percent and 4 percent of the population.
Mice that barber, or pull their hair out, have been shown to have low levels of serotonin activity in the brain. That neurotransmitter is known to affect mood and impulses. Garner hypothesized that increasing serotonin activity in the brain might cure or reduce barbering and possibly trichotillomania.
Serotonin is manufactured in the brain from the amino acid tryptophan, which is consumed in diets. The problem is that tryptophan often doesn't make it across the barrier between blood and the brain because other amino acids can get through more easily and essentially block the door for tryptophan.
Garner modified a mouse diet to increase simple carbohydrates, or sugars, and tryptophan. The sugars trigger a release of insulin, which causes muscles to absorb those other amino acids and gives tryptophan a chance to make it to the brain.
Using eight times as much sugar and four times as much tryptophan, Garner observed a doubling of serotonin activity in the brain. But the mice that barbered did not get better.
"We put them on this diet, and it made them much, much worse," Garner said.
A second experiment divided the mice into three groups: those that were seemingly normal, others that had some hair loss due to barbering and a group that had severe hair loss. All the mice soon got worse, with conditions escalating over time.
"Three-quarters of the mice that were ostensibly healthy developed one of the behaviors after 12 weeks on the new diet," Garner said.
Some of the mice developed ulcerated dermatitis, a fatal skin condition thought to be caused by an unidentified pathogen or allergen. Garner saw that the only mice that contracted the condition were the scratchers.
"What if ulcerated dermatitis, like skin-picking, another common behavioral disorder, is not really a skin disease at all?" Garner said. "We now have evidence that it may be a behavioral disorder instead."
When taken off the new diet, the negative behaviors stopped developing in the mice. When control mice were switched to the new diet, they started scratching and barbering.
Garner's study raises questions of how diet might be affecting other behavioral or mental illnesses such as autism, Tourette syndrome, trichotillomania and skin-picking. He said that before now, a link between diet and the onset of mental disorders hadn't been shown.
"What if the increase of simple sugars in the American diet is contributing to the increase of these diseases?" Garner said. "Because we fed the mice more tryptophan than in the typical human diet, this experiment doesn't show that, but it certainly makes it a possibility."
Garner next wants to refine the experiments to better imitate human dietary habits, including the amount of tryptophan people consume. Internal Purdue funding paid for his work.
Wednesday, December 29, 2010
12/29/2010 09:33:00 AM Publicado por Jorge Franchín
12/29/2010 09:31:00 AM Publicado por Jorge Franchín
Until last summer, recent discoveries of dinosaur bones and tracks in Alaska have been restricted to the Cretaceous Period.
That changed when a team including University of Alaska Fairbanks scientists documented fossilized tracks in Southwest Alaska that appear to date from the Jurassic Period, which stretches from 150 to 200 million years ago.
“In one fell swoop we pushed the record of dinosaurs in Alaska back about 50 million years,” said Patrick Druckenmiller, earth sciences curator at the University of Alaska Museum of the North and assistant professor in the UAF geology and geophysics department.
In 1975, geologists mapping the rocks near Chignik Bay discovered what appeared to be three-toed dinosaur tracks on a sandstone cliff. The group photographed the site but did not collect any other data. Thirty-five years later, Druckenmiller and a team of scientists set out to find the location in that photo and fully document the site. The team included Kevin May from the museum, UAF geologists Sarah Fowell and Paul McCarthy, and invertebrate paleontologist Robert Blodgett of Anchorage.
Planning the expedition presented logistical challenges. The field area is in remote and mountainous terrain famous for its high density of coastal brown bears. The precise location of the tracks was also uncertain, so Druckenmiller received permission to work on both Chignik Lagoon Native Corporation land and in the Alaska Peninsula National Wildlife Refuge. The work was based out of Chignik Bay, Alaska.
“It was great to land in a community that was very receptive and accommodating to the field work we had to do,” said Druckenmiller.
Supported by helicopter pilot Sam Egli of King Salmon, the team established a remote field camp and set to work. May said they found the site after only two days of searching. “After staring at the 1975 photograph for so long, it was a real thrill to finally see it in real life.”
The layer of tracks was tilted nearly vertically and could only be reached with the use of climbing equipment. Once they reached the site, Druckenmiller and May made replicas of each track for study and exhibit back at the museum.
Druckenmiller said the trip netted a surprising amount of information.
“Based on their size and shape we can tell that the tracks were made by a human-sized, meat-eating (theropod) dinosaur,” he said. “We could even see impressions from tips of their claws. That makes these tracks especially rare.”
The rest of the team examined the rocks for additional clues and were able to establish that these dinosaurs walked on sand in a beach-type environment during the Late Jurassic Period, long before modern Alaska took shape.
Druckenmiller said the findings provide an entirely new chapter in the story of the life that once existed in Alaska and he hopes to return to the site in the near future. “We are pretty sure there are other surprises waiting for us out there.”
(Photo: Kevin May, UA Museum of the North)
University of Alaska Fairbanks
12/29/2010 09:27:00 AM Publicado por Jorge Franchín
Harnessing the power of ocean tides has long been imagined, but countries are only now putting it into practice. A demonstration project planned for Puget Sound will be the first tidal energy project on the west coast of the United States, and the first array of large-scale turbines to feed power from ocean tides into an electrical grid.
University of Washington researchers are devising ways to site the tidal turbines and measure their environmental effects. Brian Polagye, UW research assistant professor of mechanical engineering, presented recent findings in an invited talk at the American Geophysical Union's annual meeting in San Francisco.
Polagye and colleagues are involved in environmental monitoring before and during a planned deployment of two 30-foot-wide turbines in Admiralty Inlet, the main entrance to Washington state's Puget Sound.
"There really isn't that much information, anywhere, about the environmental effects of tidal turbines," Polagye said.
Although European countries have more experience with tidal energy devices, they are not as far ahead on environmental monitoring, Polagye said. He believes the Pacific Northwest installation will have the most comprehensive environmental monitoring of any tidal project so far.
"The results of this pilot project will help decide if this is an industry that has potential for going forward at the commercial scale, or if it stops at the pilot stage," Polagye said.
The Snohomish County Public Utility District, just north of Seattle, received a $10 million grant from the Energy Department for the tidal project now in the final phase of obtaining permits. The turbines would generate an average of 100 kilowatts of electricity, enough to power 50-100 Washington homes during the pilot phase.
"We want to monitor the effects of this particular project, but also understand the processes so we can apply the findings to other potential tidal energy sites," Polagye said.
To do this, the UW team must assess a new technology that operates in a little-explored environment.
"There's surprisingly little known about the oceanography of these very fast waters," said collaborator Jim Thomson, a UW assistant professor of civil and environmental engineering and an oceanographer in the UW's Applied Physics Laboratory. "These kinds of tidal channels where water is going very fast only happen in a few areas, and have not been well studied. The currents are so fast that it's hard to operate vehicles and maintain equipment. And it's too deep for conventional scuba diving."
The pilot site lies roughly 200 feet below the surface of Admiralty Inlet, where the UW team has measured currents of up to 8 knots, or 9 miles per hour.
One area of concern is how underwater noise generated by the turbines could affect marine mammals that use auditory cues to navigate and communicate with each other. Strong currents complicated the task of measuring how sound travels in the channel.
"When currents were more than about 2 knots the instruments are hearing considerable self-noise," Polagye said. "It's similar to when you're bicycling downhill and the air rushes past your ears." Chris Bassett, a UW doctoral student in mechanical engineering, is testing approaches that would allow underwater microphones to work in fast-moving water.
UW researchers used sound from a Washington state ferry to learn how turbine noise would spread from the project site. The data suggest that Admiralty Inlet tends to lessen sound. This reduces the effect on animals' hearing, which is good, but it also means less noise for marine mammals to detect turbines and avoid them.
The UW team has been measuring currents continuously at the proposed site for almost two years, using a monitoring tripod the size of a small refrigerator. With added ballast for stability, the device weighs 850 pounds in water. Even so, it can barely stay put on the ocean floor.
The monitoring tripod holds instruments to track water quality, ambient noise, currents, temperature and salinity, and to record marine mammal calls and electronic tags on passing fish. This observational data will help determine precisely where to put the tidal turbines, and establish potential environmental effects once they are in the water.
So far, researchers say, the data support the notion that the Admiralty Inlet is well suited for a tidal energy installation from an engineering perspective. Once the turbines are in the water, likely in 2013, researchers will monitor environmental effects.
The Admiralty Inlet characterization is being conducted by the Northwest National Marine Renewable Energy Center, in which the UW leads research on tidal energy. Polagye and Thomson lead research on characterizing the physical attributes, such as currents and sound propagation. UW fisheries scientists recently received funding to test instruments for monitoring fish at the site, UW mechanical engineers are using computer models to see how pressure changes caused by tidal turbines could affect sediments and fish, and UW oceanographers are calculating when turbines would begin to affect the Sound's tides and currents.
The Washington state deployment is among three U.S. tidal energy pilot projects now in the works (the others are in Maine and Alaska). An array of smaller turbines was operated during a pilot project in New York City's East River.
(Photo: OpenHydro Technology Ltd.)
University of Washington