Drastic weight loss can trigger anorexia in obese

Severely obese people can potentially develop anorexic and bulimic symptoms after they have lostweight through strict dieting or stomach-reduction surgery, Spanish researchers report.

The flip-flop, they say, appears to come from an intense, obsessive fear of regaining weight–supporting the idea that obesity and eating disorders share some features.

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New NIH grant program sends foreign scholars home

With its newest funding program, the Fogarty International Center (FIC), part of the US National Institutes of Health (NIH), is hoping to stem at least in part the chronic brain drain of scientists that plagues poor and developing nations.

The Global Health Research Initiative Program (GRIP), announced this week, gives desperately needed money – up to $50,000 per year for five years – to allow US-trained foreign scientists to continue their research and set up labs after their return home.
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Tree genome project should speed ultraslow science

An international team of researchers led by the US Department of Energy (DOE) has announced that it will sequence Populus, the first tree genome, by as early as December 2002.
The agency hopes the effort will lead to advances in phytoremediation, carbon sequestration, and biofuels production. Scientists also hope to learn what is the genomic difference between a little weed and a huge tree.

“Trees, unlike annual plants such as Arabidopsis, have to withstand environmental fluctuations throughout the year, and year to year,” said project scientist Gerald Tuskan, who works at the DOE’s Oak Ridge National Laboratory. “A tree genome sequence gives us the opportunity to find adaptive genes, such as those involved in drought tolerance, cold and disease resistance, and photo period responses.”

The genus Populus is comprised of well-studied, fastgrowing trees such as cottonwoods, poplar, and aspen. The DOE has been studying the genus for the last twenty years for its potential use as feedstock and ethanol production.

Perhaps the most important reason that Tuskan and his colleagues from the University of Washington, Genome Canada, and the Swedish University of Agricultural Sciences decided to sequence Populus first was because its genome was relatively small. It is only about 550 million base pairs long – about four times the size of Arabidopsis and one of the smallest genomes of a commercially important tree species, notes Jeffrey Dean, a researcher at the University of Georgia.

“Eucalyptus is the only other tree species that could be worthy of consideration for this type of project,” said Dean, who specializes in forest-tree biotechnology. “Even though conifers, especially pines, are much more commercially important, their genomes are enormous,” he added.

The Populus genome is about 40 times smaller than that of pine, added Toby Bradshaw, a project scientist at the University of Washington.

“By having an unabridged list of all the genes in a forest tree, we can ask questions like: ‘Do trees have a set of ‘unique’ genes that are responsible for the unique aspects of their biology (such as extensive wood formation, complex crown architecture, vegetative dormancy, and pronounced juvenile-mature transition)?’” added Bradshaw. “Or do trees share all their genes with herbaceous plants such as Arabidopsis, but regulate these genes differently to produce the dramatic tree?”

The DOE’s goal is to sequence a minimum of 90% of the Populus genome; a 6x draft will be completed in two 3x stages over the next two fiscal years. The drafting, which will be conducted by the agency’s Joint Genome Institute, is expected to cost $25 million, said Tuskan. “This will not be an annotated genome, or a whole genome chip, or a SNP library” he said.

“Developing a gene platform will probably cost five to ten times the initial investment,” he added. Most likely DOE and the National Science Foundation will issue research funding proposals to do this work, he said.

DOE is hoping to use insights gained from a completed genome to discover ways to genetically modify trees that can then be used for producing ethanol, cleaning hazardous waste sites and removing carbon dioxide from the atmosphere, says Tuskan.

“For example, if we understood cell-wall biosynthesis in total, maybe then we can manipulate the ratio of cell-wall compounds – cellulose, hemicellulose, and lignin. If we were after greater ethanol conversion, then we would try to make the tree produce higher amounts of cellulose,” he said. “But for carbon sequestration, we’d want to enhance the amount of lignin, to make the wood decay resistant.” The same could be done for disease resistance and phytoremediation.

A completed tree genome sequence would also benefit the broader academic community of plant scientists and forest biologists, especially in the fields of silviculture and comparative genetics.

“Cataloging the complete genetic makeup of a tree will allow us to also do things other than just manipulating and changing the genotype of trees,” said Dean. “We would be able to monitor the physiological responses of trees to their environment.

“One of limitations we have in forestry is that wood is produced via a fairly long, slow process,” he went on. “It’s very difficult to run an experiment – for example, adding extra fertilizer or water, or trimming branches – and then know within a few days or weeks whether or not the tree is responding to the treatment.”

“With a genomic tool like DNA microarray, we can potentially go out and assess in a day or two if the tree’s metabolism is responding to a treatment,” he said.

Big Blue

Children’s dentist Elvir Dincer recalls the worst case he ever worked on. “A three-year-old who, his school had told me, was not eating properly. He was anemic and his physician had been loading him up with iron supplements.” When Dincer examined the child’s teeth, he couldn’t believe what he saw.
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Explaining Tip-of-the-Tongue Experiences

ou’re at a restaurant with a friend, and he’s just finished describing a movie he really enjoyed. “That reminds me,” you say, “you just have to see, um….”
Some of us have these frustrating tip-of-the-tongue (TOT) experiences all too often, and a new study published in the November issue of the Journal of Experimental Psychology: Learning, Memory and Cognition suggests they stem from the brain’s inability to make strong enough connections among the various sound parts needed to form a sought-after word. “There are two levels in getting a word,” explains Pomona College psychologist Deborah M. Burke, one of the authors of the study. “First, you have to select the specific word you want, and then you have to get the sound code for that word from memory. In a TOT experience, we’re saying that people have the idea, the conceptual or semantic information about a word–and even know they’ve got a word to express it–but they just can’t retrieve the sounds.”

The notion that TOTs occur because of weak connections among stored sounds is known as the transmission deficit (TD) model. Burke and her husband, psychologist Don MacKay, proposed the model in 1991 as an alternative to the widely accepted inhibition, or “blocking,” hypothesis, which suggests that TOTs occur because words that sound like an intended word block its retrieval. To test the TD model, Burke and her current collaborator, Lori E. James of the University of California at Los Angeles, designed two experiments in which they asked 108 people to answer a variety of general-knowledge questions; the answers were target words known to provoke a high rate of TOTs. The participants responded with the answer, “TOT” or “Don’t Know.”

In the first experiment, participants had to pronounce a list of 10 words before seeing the question. Sometimes the list contained words that had nothing in common with the target word. Other times, however, the list contained five “priming words”–words that were phonologically related to the target word. As expected, when participants pronounced words sharing sounds with the target word, they made more correct responses and had fewer TOT experiences than when they pronounced words that had no phonological relation to the target word.

In the second experiment, participants answered the question without any list. Only if they entered a “Don’t Know” response or experienced a TOT state were they then given a list. Again, the researchers found that in cases where the participants had initially answered TOT, their probability of resolving the word increased 25 to 50 percent if they were then primed with phonologically similar words. These findings refute the blocking hypothesis, the authors argue, which would have predicted exactly the opposite results.