20091211-3

This device uses magnetic fields to separate cells by size and shape.
Credit: Hur Koser

 
A new device separates healthy and diseased cells.

 

MIT Technology Review, December 10, 2009, by Katherine Bourzac  —  Researchers at Yale have demonstrated a device that uses a magnetic liquid to separate blood cells based on their size and shape in just minutes.

The device applies a magnetic field to a liquid containing magnetic nanoparticles. The nanoparticles create waves that carry cells along depending on their size, shape and mechanical properties. The researchers, led by electrical engineering professor Hur Koser, hope to develop a cheap alternative to cell-sorting techniques that are time-consuming and sometimes require expensive labeling.

Liquid suspensions of magnetic particles, called ferrofluids, are already used as industrial lubricants and in loudspeakers and computer hard disks. These liquids typically contain other chemicals to keep the particles from clumping together and from coming out of the suspension. Magnetic nanoparticles are also being explored for cancer therapies and as contrast agents for magnetic resonance imaging (MRI)–both applications that require very low concentrations.

But the Yale group is the first to make a high-concentration, biocompatible ferrofluid that doesn’t contain any chemicals that are harmful to cells, yet still keeps the particles afloat. “It was very tricky to find the parameters to maintain live cells,” says Koser.

In experiments described this week in the Proceedings of the National Academy of Sciences, the Yale researchers made microfluidic channels lined with magnetic-field-generating electrodes. Cells were then added to a ferrofluid in the channel. When magnetic fields were applied along the device, the particles in the fluid pushed the cells along the channel, separating them by size and shape. Something similar can be accomplished using electrical fields, says Koser, but this can damage the cells. His group used the device to separate live blood cells from sickle cells and bacteria.

Koser believes the device could be especially helpful when trying to detect very rare types of blood cell, such as cancerous ones. Rapidly sorting cells using magnetic fields could improve the sensitivity of tests for these rare cells without adding any costly chemical labels. Tumor cells are squishier than healthy ones–possibly because they grow quickly and so don’t form a proper internal cell skeleton–and Koser hopes that magnetic fields will also be able to separate cells based on their elasticity and other mechanical properties.

“The next step is to try this in conjunction with existing sensors to improve their sensitivity and cut down on time,” says Koser.

In the video below, a magnetic field creates waves in a liquid containing magnetic nanoparticles (the nanoparticles are not visible) to separate two types of microbeads based on their size.

http://www.technologyreview.com/blog/editors/

Scientists Engineer Stem Cells to Fight HIV

The approach might provide a way to prime the immune system against a variety of diseases.

MIT Technology Review, December 10, 2009, by Emily Singer  —  Stem cells genetically engineered to carry a molecule (derived from an HIV-infected person) that recognizes the virus could provide a new way to bolster the immune system against the disease, according to new research published this week in PLoS ONE. When implanted into mice, the stem cells developed into mature immune cells that could target cells with HIV specific proteins. Researchers are using a similar approach to prime the human immune system against cancer.

“We have demonstrated in this proof-of-principle study that this type of approach can be used to engineer the human immune system, particularly the T-cell response, to specifically target HIV-infected cells,” says lead investigator Scott G. Kitchen, an assistant professor of medicine in the division of hematology and oncology at the David Geffen School of Medicine at UCLA and a member of the UCLA AIDS Institute, in a press release. “These studies lay the foundation for further therapeutic development that involves restoring damaged or defective immune responses toward a variety of viruses that cause chronic disease, or even different types of tumors.”

According to the release:

Taking CD8 cytotoxic T lymphocytes–the “killer” T cells that help fight infection–from an HIV-infected individual, the researchers identified the molecule known as the T-cell receptor, which guides the T cell in recognizing and killing HIV-infected cells. These cells, while able to destroy HIV-infected cells, do not exist in enough quantities to clear the virus from the body. So the researchers cloned the receptor and genetically engineered human blood stem cells, then placed the stem cells into human thymus tissue that had been implanted in mice, allowing them to study the reaction in a living organism.

The engineered stem cells developed into a large population of mature, multifunctional HIV-specific CD8 cells that could specifically target cells containing HIV proteins. The researchers also found that HIV-specific T-cell receptors have to be matched to an individual in much the same way that an organ is matched to a transplant patient.

Researchers hope the technology will have broader applications.”This approach could be used to combat a variety of chronic viral diseases,” says co-author Jerome A. Zack, a UCLA professor of medicine in the division of hematology and oncology and associate director of the UCLA AIDS Institute, in the same release. “It’s like a genetic vaccine.”

20091211-2

Most female patients describe each cluster headache attack as worse than childbirth.

 

LATimesblogs.LATimes.com, December 10, 2009  —  A study that came out 12/09/09 in the Journal of the American Medical Assn. concludes that cluster headaches can be treated by inhaling pure 100% oxygen.

Cluster headaches affect about 0.3% of the general population, according to the study. The National Institutes of Health says the debilitating headaches can strike daily for weeks at a time. Other sources say the bouts can last for months before patients go into remission.

Migraine drugs such as Imitrex (sumatriptan) are typically prescribed to stop the pain, but there are limits on daily usage. A small study of 15 patients has found that inhaling high-flow oxygen for 15 minutes was helpful. A trio of researchers from the National Hospital for Neurology and Neurosurgery in London decided to test the therapy more rigorously.

They found 76 patients who suffered cluster headaches and treated them for four attacks. They were asked to inhale either pure oxygen or normal air (which includes 21% oxygen) through a face mask for 15 minutes. Neither the patients nor the providers knew which odorless, colorless gas was being administered.

But there was a difference. When asked to rate their pain relief, 78% of patients said they felt fine within 15 minutes of breathing high-flow pure oxygen. By contrast, only 20% of patients had the same response after being treated with high-flow regular air. Oxygen continued to outperform air at 30 and 60 minutes after the onset of the attack, according to the study. The researchers didn’t report any serious adverse effects.

The study was funded in part by Linde Industrial Gases, a German supplier of industrial and medical gases. One of the study’s authors disclosed that he had served on a Linde advisory board about the use of oxygen to treat cluster headaches.

— Karen Kaplan

Photo illustration: Excruciating headache? Oxygen may help. Credit: Gary Friedman / Los Angeles Times

 

LATimesblogs.LATimes.com

Most of us spend our days on our behinds – and it’s killing us

20091211-1

When you sit for an extended period of time, your circulation slows and you burn fewer calories. Key flab-burning enzymes responsible for breaking down triglycerides (a type of fat) simply start switching off.
Emmanuel Faure/Corbis stock

By Selene Yeager

www.MSNBC.MSN.com, December 10, 2009 — You might not want to take the following stat sitting down: According to a poll of nearly 6,300 people by the Institute for Medicine and Public Health, it’s likely that you spend a stunning 56 hours a week planted like a geranium – staring at your computer screen, working the steering wheel, or collapsed in a heap in front of your high-def TV. And it turns out women may be more sedentary than men, since they tend to play fewer sports and hold less active jobs.

Even if you think you have an energetic lifestyle, sitting is how most of us spend a good part of our day. And it’s killing us – literally – by way of obesity, heart disease, and diabetes. All this downtime is so unhealthy that it’s given birth to a new area of medical study called inactivity physiology, which explores the effects of our increasingly butt-bound, tech-driven lives, as well as a deadly new epidemic researchers have dubbed “sitting disease.”

The modern-day desk sentence
“Our bodies have evolved over millions of years to do one thing: move,” says James Levine, M.D., Ph.D., of the Mayo Clinic in Rochester, Minn., and author of “Move a Little, Lose a Lot.” “As human beings, we evolved to stand upright. For thousands of generations, our environment demanded nearly constant physical activity.”

Burn more calories

Instead of this:

Cal/hr

Do this:

Cal/hr

Sitting at your desk

83

Stand at your desk

115

Riding the elevator

128

Take the stairs

509

Shopping online

96

Shop at the mall (walking briskly and carrying packages)

147

Calling for takeout

96

Cook at home

128

Talking on the phone seated

102

Pace while chatting

147

E-mailing a coworker

96

Walk to her office

128

Watching TV

64

Make out

96

Playing a seated video game

32

Play Wii

178

TOTAL CALORIES

697

TOTAL CALORIES

1,448

But thanks to technological advances, the Internet, and an increasingly longer work week, that environment has disappeared. “Electronic living has all but sapped every flicker of activity from our daily lives,” Levine says. You can shop, pay bills, make a living, and with Twitter and Facebook, even catch up with friends without so much as standing up. And the consequences of all that easy living are profound.

When you sit for an extended period of time, your body starts to shut down at the metabolic level, says Marc Hamilton, Ph.D., associate professor of biomedical sciences at the University of Missouri. When muscles – especially the big ones meant for movement, like those in your legs – are immobile, your circulation slows and you burn fewer calories. Key flab-burning enzymes responsible for breaking down triglycerides (a type of fat) simply start switching off. Sit for a full day and those fat burners plummet by 50 percent, Levine says.

That’s not all. The less you move, the less blood sugar your body uses; research shows that for every two hours spent on your backside per day, your chance of contracting diabetes goes up by 7 percent. Your risk for heart disease goes up, too, because enzymes that keep blood fats in check are inactive. You’re also more prone to depression: With less blood flow, fewer feel-good hormones are circulating to your brain.

Spending the day on your rear is also hell on your posture and spine health, says Douglas Lentz, a certified strength and conditioning specialist and the director of fitness and wellness for Summit Health in Chambersburg, Pa. “When you sit all day, your hip flexors and hamstrings shorten and tighten, while the muscles that support your spine become weak and stiff,” he says. It’s no wonder that the incidence of chronic lower-back pain among women has increased threefold since the early 1990s.

And even if you exercise, you’re not immune. Consider this: We’ve become so sedentary that 30 minutes a day at the gym may not do enough to counteract the detrimental effects of eight, nine, or 10 hours of sitting, says Genevieve Healy, Ph.D., a research fellow at the Cancer Prevention Research Centre of the University of Queensland in Australia. That’s one big reason so many women still struggle with weight, blood sugar, and cholesterol woes despite keeping consistent workout routines.

In a recent study, Healy and her colleagues found that regardless of how much moderate to vigorous exercise participants did, those who took more breaks from sitting throughout the day had slimmer waists, lower BMIs (body mass indexes), and healthier blood fat and blood sugar levels than those who sat the most. In an extensive study of 17,000 people, Canadian researchers drew an even more succinct conclusion: The longer you spend sitting each day, the more likely you are to die an early death – no matter how fit you are.

The non-exercise answer
So if exercise alone isn’t the solution, what is? Fortunately, it’s easier than you think to ward off the perils of prolonged parking. Just ramp up your daily non-exercise activity thermogenesis – or NEAT. That’s the energy (i.e., calories) you burn doing everything but exercise. It’s having sex, folding laundry, tapping your toes, and simply standing up. And it can be the difference between wearing a sarong or flaunting your bikini on your next beach vacation.

In his groundbreaking study on NEAT, the Mayo Clinic’s Levine used motion-sensing underwear (hot, huh?) to track every single step and fidget of 20 people who weren’t regular exercisers (half of them were obese; half were not). After 10 days, he found that the lean participants moved an average of 150 minutes more per day than the overweight people did – enough to burn 350 calories, or about one cheeseburger.

Fidgeting, standing, and puttering may even keep you off medications and out of the doctor’s office. Think of your body as a computer: As long as you’re moving the mouse and tapping the keys, all systems are go. But let it idle for a few minutes, and the machine goes into power-conservation mode. Your body is meant to be active, so when you sit and do nothing for too long, it shuts down and burns less energy. Getting consistent activity throughout the day keeps your metabolism humming along in high gear.

When you get out of your chair and start moving around, you turn on fat burners. Simply standing up fries three times as many calories as sitting on your butt, according to Levine. And, he adds, “NEAT activity can improve blood flow and increase the amount of serotonin available to the brain, so that your thinking becomes sharper and you’ll be less likely to feel depressed.”

Get your move on
Shake things up throughout the day by interrupting your sedentary stints as often as possible. “Stand up every half hour,” says Neville Owen, Ph.D., of the University of Queensland. “If you have to sit for longer than that, take more extended and active breaks and move around for a few minutes before sitting back down.”

When you’re reading e-mail and taking phone calls, do it standing. Walk with colleagues to brainstorm ideas. And consider trading your chair for a large stability ball. “It forces you to engage your muscles, and you’re likely to stand up more because you’re not melting into a chair,” Lentz says.

At home, it’s simple: Limit TV time to two hours a day or less. Better yet, watch it from a treadmill or exercise bike. Among women, the risk for metabolic syndrome – a constellation of health woes including high blood pressure, high cholesterol, and high blood sugar – shoots up 26 percent for every hour per day they spend watching the tube.

Not sure how much of a difference these mini moves will make? Swapping a more active approach for just a few of your daily activities can help stave off the one-to two-pound weight gain most women accumulate every year – and it can keep your metabolism buzzing the way nature intended it to.