“Alex, I’ll take “What are birds?” for $20.”
New key to flu's spread discovered
Finding could help scientists better monitor changes in deadly H5N1 virus (MSNBC)
CHICAGO - Flu viruses must be able to pick a very specific type of lock before entering human respiratory cells, U.S. researchers said on Sunday, offering a new understanding of how flu viruses work.
The discovery may help scientists better monitor changes in the H5N1 bird flu virus that could trigger a deadly pandemic in humans. And it may lead to better ways to fight it, they said.
The scientists found that a flu virus must be able to attach itself to an umbrella-shaped receptor coating human respiratory cells before it can infect cells in the upper airways.
"What the lock needs is the right key. It opens the door," said Ram Sasisekharan, a professor of biological engineering and health sciences at Massachusetts Institute of Technology in Cambridge.
The H5N1 avian flu virus now almost exclusively infects birds. But it can occasionally pass to a person.
Experts have feared that the bird flu virus would evolve slightly into a form that people can easily catch and pass to one another, triggering an epidemic.
"We now know what to look for," said Sasisekharan, whose study appears in the journal Nature Biotechnology.
Before a flu virus can enter a human respiratory cell, a protein on the surface of the virus must bind with chains of sugars called glycans that sit on the outside of the cells.
Scientists have classified these chains according to how they are linked together chemically. In birds, the virus binds with alpha 2-3 receptors; in humans, it binds with alpha 2-6 receptors.
To infect humans, scientists thought the H5N1 bird flu virus would need to simply mutate so it could bind with alpha 2-6 receptors. But it turns out not all alpha 2-6 receptors are the same. Some are short and cone-shaped and some are long and umbrella-shaped.
"Defining human and bird receptors just by linkage forgets to take shape into account," Sasisekharan said in a telephone interview.
Virus surveillance
Shape difference may explain why humans can get bird flu from a bird and not pass it along easily to other humans, he said.
So far, the bird flu virus has found a way to bind only to the cone-shaped structures in human upper airways. The virus has already killed 216 people and infected 348 people in 14 countries, according to the World Health Organization.
But the study found that the most infectious human flu viruses bind with the umbrella-shaped receptors in the upper respiratory tract. The researchers believe the H5N1 bird flu virus would need to adapt so it could latch on to these umbrella-shaped receptors before it could be spread readily from human to human.
Understanding this mechanism could lead to better surveillance of changes in the virus and may lead to the development of new and better drugs to treat flu viruses.
"It opens up ways for people to bring in different kinds of small molecule approaches for new drug development," Sasisekharan said, adding the work could help seasonal flu sufferers as well.
What’s passing for science this week?
Advice changes for preventing baby allergies
No good evidence for strategies other than breast-feeding
CHICAGO (MSNBC) - Breast-feeding helps prevent babies’ allergies, but there’s no good evidence for avoiding certain foods during pregnancy, using soy formula or delaying introduction of solid foods beyond six months.
That’s the word from the American Academy of Pediatrics, which is updating earlier suggestions that may have made some parents feel like they weren’t doing enough to prevent food allergies, asthma and allergic rashes.
In August 2000, the doctors group advised mothers of infants with a family history of allergies to avoid cow’s milk, eggs, fish, peanuts and tree nuts while breast-feeding.
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That advice, along with a recommended schedule for introducing certain risky foods, left some moms and dads blaming themselves if their children went on to develop allergies.
“They say, ’I shouldn’t have had milk in my coffee,”’ said Dr. Scott Sicherer of the Mount Sinai School of Medicine’s Jaffe Food Allergy Institute in New York. “I’ve been saying, ’We don’t really have evidence that it causes a problem. Don’t be on a guilt trip about it.”’
Sicherer helped write the new guidance report for pediatricians, published in the January issue of the journal Pediatrics. Earlier advice about restricting certain foods from moms’ and babies’ diets has been tossed out and the only surefire advice remaining is to breast-feed.
The report says:
* There is no convincing evidence that women who avoid peanuts or other foods during pregnancy or breast-feeding lower their child’s risk of allergies.
* For infants with a family history of allergies, exclusive breast-feeding for at least four months can lessen the risk of rashes and allergy to cow’s milk.
* Exclusive breast-feeding for at least three months protects against wheezing in babies, but whether it prevents asthma in older children is unclear.
* There is modest evidence for feeding hypoallergenic formulas to susceptible babies if they are not solely breast-fed.
* There is no good evidence that soy-based formulas prevent allergies.
* There is no convincing evidence that delaying the introduction of foods such as eggs, fish or peanut butter to children prevents allergies. Babies should not get solid food before 4 to 6 months of age, however.
The evidence for the earlier recommendations was weak and hasn’t been strengthened by new research, Sicherer said.
“You never know what’s going to come around the corner, but in the past seven years there hasn’t been enough evidence to support the old recommendations,” Sicherer said.
Dr. Peter Vadas of the University of Toronto conducted prior research that found peanut protein in breast milk. His work has been cited as a reason for nursing mothers to avoid eating peanuts.
Vadas said he advises breast-feeding mothers to avoid peanuts, but only if there is a family history of peanut allergy, and he makes it clear the advice is arguable.
“There’s really no reason to engage in a lot of dietary manipulation except in very specific instances,” Vadas said.
Better living through chemistry
Watching Roger Clemens do his Hillary Clinton impression—priceless.
Headline of the day
Fire Chief Under Fire Over E-Mailed Photos Of Topless Crash Victim
(Local6.com/Orlando)
Your tax dollars at work
Late night television advertising revenues set to jump dramatically
Healing Value Of Magnets Demonstrated In Biomedical Engineering Study
ScienceDaily (Jan. 7, 2008) — A recent study demonstrates that the use of an acute, localized static magnetic field of moderate strength can result in significant reduction of swelling when applied immediately after an inflammatory injury. Magnets have been touted for their healing properties since ancient Greece. Magnetic therapy is still widely used today as an alternative method for treating a number of conditions, from arthritis to depression, but there hasn’t been scientific proof that magnets can heal.
Lack of regulation and widespread public acceptance have turned magnetic therapy into a $5 billion world market. Hopeful consumers buy bracelets, knee braces, shoe inserts, mattresses, and other products that are embedded with magnets based on anecdotal evidence, hoping for a non-invasive and drug-free cure to what ails them.
“The FDA regulates specific claims of medical efficacy, but in general static magnetic fields are viewed as safe,” notes Thomas Skalak, professor and chair of biomedical engineering at U.Va.
Skalak has been carefully studying magnets for a number of years in order to develop real scientific evidence about the effectiveness of magnetic therapy.
Skalak’s lab leads the field in the area of microcirculation research—the study of blood flow through the body’s tiniest blood vessels. With a five-year, $875,000 grant from the National Institutes of Health’s National Center for Complementary and Alternative Medicine, Skalak and Cassandra Morris, former Ph.D. student in biomedical engineering, set out to investigate the effect of magnetic therapy on microcirculation. Initially, they sought to examine a major claim made by companies that sell magnets: that magnets increase blood flow.
The researchers first found evidence to support this claim through research with laboratory rats. In their initial study, magnets of 70 milliTesla (mT) field strength—about 10 times the strength of the common refrigerator variety—were placed near the rat’s blood vessels. Quantitative measurements of blood vessel diameter were taken both before and after exposure to the static magnetic fields—the force created by the magnets. Morris and Skalak found that the force had a significant effect: the vessels that had been dilated constricted, and the constricted vessels dilated, implying that the magnetic field could induce vessel relaxation in tissues with constrained blood supply, ultimately increasing blood flow.
Dilation of blood vessels is often a major cause of swelling at sites of trauma to soft tissues such as muscles or ligaments. The prior results on vessel constriction led Morris and Skalak to look closer at whether magnets, by limiting blood flow in such cases, would also reduce swelling. Their most recent research, published in the November 2007 issue of the American Journal of Physiology, yielded affirmative results.
In this study, the hind paws of anesthetized rats were treated with inflammatory agents in order to simulate tissue injury. Magnetic therapy was then applied to the paws. The research results indicate that magnets can significantly reduce swelling if applied immediately after tissue trauma.
Since muscle bruising and joint sprains are the most common injuries worldwide, this discovery has significant implications. “If an injury doesn’t swell, it will heal faster—and the person will experience less pain and better mobility,” says Skalak. This means that magnets could be used much the way ice packs and compression are now used for everyday sprains, bumps, and bruises, but with more beneficial results. The ready availability and low cost of this treatment could produce huge gains in worker productivity and quality of life.
Skalak envisions the magnets being particularly useful to high school, college, and professional sports teams, as well as school nurses and retirement communities. He has plans to continue testing the effectiveness of magnets through clinical trials and testing in elite athletes. A key to the success of magnetic therapy for tissue swelling is careful engineering of the proper field strength at the tissue location, a challenge in which most currently available commercial magnet systems fall short. The new research should allow Skalak’s biomedical engineering group to design field strengths that provide real benefit for specific injuries and parts of the body.
“We now hope to implement a series of steps, including private investment partners and eventually a major corporate partner, to realize these very widespread applications that will make a positive difference for human health,” says Skalak.
This just in, Ron Popeil nominated for Nobel in medicine.
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