contemplatingmadness:

Your DNA Changes as You Age

While our bodies age, scientists believe that our DNA at least remains constant. New research, however, reveals that, even though its sequence remains constant, subtle chemical changes occur to our DNA as we age—and it could explain why the risk of developing disease increases as we get older.

DNA is made up of four basic chemical building blocks, called adenine, thymine, guanine, and cytosine. It’s the sequences of those chemicals in a strand of DNA that determines what function a gene has, and one of the ways the resulting genes are controlled is a process called methylation. That just means that a methyl group — one carbon atom and three hydrogen atom—bonds to part of the DNA and subtly change its function.

New research, published in PNAS, however, shows that as we grow older our DNA’s susceptibility to methylation changes. A team of researchers from the Bellvitge Biomedical Research Institute in Barcelona, Spain, extracted DNA from white blood cells of twenty newborn babies and twenty people aged between 89 and 100 years old, then compared their respective degrees of methylation.

In a newborn baby 80.5 percent of cytosine nucleotides were methylated, while in centenarians that figure dropped to 73 percent. An intermediary example, taken from a 26-year-old male subject, exhibited 78 percent methylation. It’s not clear why it happens, but the researchers speculate that it could be due to extremely subtle age-related changes to the DNA.

But what the hell does it all mean? Well, taking a closer look at the samples, the researchers discovered that a third of the methylated groups which were in different positions in the elderly compared to the young are already known to be linked to cancer risk.

If you think about the DNA strand as “hardware” and the added methyl groups as “software”—which isn’t actually a bad analogy—you can think of the inappropriately placed methyl groups as software bugs that accumulate with age. It’s just that, for humans, those bugs leads to increased risk of terminal disease. Fortunately, these kinds of findings should help scientists troubleshoot our internal apps. [PNAS via Science]

Genome Analysis homes in on Malaria-Drug Resistance
Researchers find genetic changes that may reduce effectiveness of artemisinin.

Researchers have identified a region of the malaria-parasite genome that underlies resistance to the most effective current treatment. The finding comes as drug resistance seems to be spreading in Southeast Asia.

Artemisinin has become the go-to treatment nearly everywhere that malaria is endemic. Resistance to it was first identified in 2005 in western Cambodia. Resistance does not necessarily cause artemisinin treatment to fail completely, but it does slow the clearance of the malaria-causing parasite Plasmodium falciparum from patients’ blood.

Researchers are concerned that artemisinin-resistant strains of P. falciparum will spread to sub-Saharan Africa, as has occurred with other malaria treatments such as chloroquine and antifolate drugs.

To find the causes of artemisinin resistance, Ian Cheeseman, a geneticist at the Texas Biomedical Research Institute in San Antonio, and his colleagues compared Cambodian, Thai and Laotian P. falciparumpopulations that had differing clearance rates after artemisinin treatment. Their results are published in Science today¹. (Read More)

Melissa Lee Phillips, Nature

Petite Particle Accelerator: A Proton Gun For Killing Tumors

Since 1990, doctors have been regularly treating cancer patients using proton beams, which work similarly to radiation. Proton therapy is more precise, however, causing less harm to healthy surrounding tissues. Unfortunately, generating a proton beam requires a particle-accelerator facility that’s the size of an airplane hangar and costs more than $100 million to build. Thus, proton-beam therapy remains a rarity, with only 37 working facilities worldwide, 10 of which are located in the U.S. Just 10,000 people were treated last year, less than 5 percent of suitable patients.

Now scientists at the Compact Particle Acceleration Corporation in Livermore, California, are developing a 13-foot-long particle accelerator that costs about $30 million. Most accelerators use large magnets to generate the electromagnetic field that pushes charged particles. The magnets require 10-foot-thick concrete shielding and bulky hardware. CPAC’s prototype creates the electromagnetic field with electric lines, which don’t require massive shielding or large additional equipment. The new accelerator could be commercially available as soon as 2015. (The numbers below will match you up to the location in the picture above.)

1. PROTON BEAM Magnets in the kicker pull positively charged protons from hydrogen plasma made by a duoplasmatron. A deflecting magnet collects the stream into proton bundles, which then enter the injector, where a microwave field speeds the particles toward the acceleration chamber at up to five million mph.

2. LASER At nearly the same time, a laser fires a light pulse, which splits into fiber-optic cables of various lengths.

3. ACCELERATION CHAMBER As a bundle of protons enters the acceleration chamber, a light pulse hits the chamber’s first pair of electric lines, triggering the release of electrons. The resulting electromagnetic field propels the proton bundle forward. The light pulse triggers the electric lines in a wave, sequentially accelerating the proton bundle until it’s traveling at 335 million mph—or about half the speed of light.

4. CLOCK The entire process is controlled by a clock, which directs magnets to turn on or off and the laser to fire.

5. ROBOTIC CHAIR Moving a patient is easier than moving a 13-foot-long particle accelerator. A robotic chair maneuvers a strapped-in patient in front of the proton beam to target a tumor from different angles.

Spencer Woodman

‘Antimagnet’ renders magnets invisible — Magnetic cloak could bring medical benefits — and security risks.

Physicists have already unveiled invisibility cloaks that can hide objects from light, sound, seismic and even water waves. Now researchers report a cloak that can hide objects from static magnetic fields. This ‘antimagnet’ could have medical applications, but might also subvert airport security.

Writing in Science¹, a team of theorists led by Alvaro Sanchez at the Autonomous University of Barcelona in Spain, together with experimentalists at the Slovak Academy of Sciences in Bratislava, describe a magnetic cloak made with inexpensive, readily available materials.

The cloak’s interiorpel external field lines, whereas the ferromagnet tries to draw them in — together, the two layers cancel each other out. To test the antimagnet, the Slovak group cooled the cloak with liquid nitrogen to activate the superconductor, and placed it in a static, uniform magnetic field with a strength of 40 millitesla. Using a measuring device called a Hall probe to map the magnetic field, the researchers found that the field lines did not enter the cloak, even through from the outside they appeared to pass straight through. They say that theirs is an ‘exact’ cloak — one for which the cloaking could, in principle, be made perfect using currently available materials. (Read More)