Tag Archives: pain

BigBang

A Painful End

This should come as no surprise — advances to our understanding of biochemical and genetic processes seem to make the news with ever-increasing regularity. Researchers seem to have found the mechanism for switching physical pain on and off in mammals. They recently succeeded in blocking and restoring pain signals in mice. And, through the same discovery have been able to restore the sensation in a woman who has an extremely rare condition that makes her unable to feel any pain. It’s all in the Nav1.7 sodium ion channel and in its regulation of opioid peptides.

Fascinating, but where will this lead us? And, more to the point, will there ever be a pill to end the interminable pain of the US political process?

From ars technica:

Physical pain is a near universal problem, whether its sudden pangs or chronic aches. Yet, researchers’ efforts to quash it completely have fallen short—possibly due to a moonlighting channel in nerve cells. But that may be about to change.

The sodium ion channel, called Nav1.7, helps generate the electrical signals that surge through pain-related nerve cells. It’s known to play a key role in pain, but researchers’ past attempts to power-down its charged activities did little to soothe suffering. In a bit of a shocking twist, researchers figured out why; the channel has a second, un-channel-like function—regulating painkilling molecules called opioid peptides. That revelation, published in Nature Communications, provided researchers with the know-how to reverse painlessness in a woman with a rare condition, plus make mice completely pain free.

The link between Nav1.7 and opioid painkillers is “fascinating,” Claire Gaveriaux-Ruff, a pain researcher and professor at the University of Strasbourg, told Ars. And, she added, “this discovery brings hope to the many patients suffering from pain that are not yet adequately treated with the available pain medications.”

That source of hope has been a long time coming, John N. Wood, lead author of the study and a neuroscientist at University College London, told Ars. Researchers have been interested in Nav1.7 for years, he said. Excitement peaked in 2006 when scientists reported finding a family who lacked the channel and could feel no pain at all. After that, researchers excitedly scrambled to relieve pain with Nav1.7-blocking drugs. But the drugs inexplicably failed, Wood said. “So we thought, well maybe this channel isn’t just a channel, maybe it’s got some other activities as well.”

Using genetically engineered mice, Wood and colleagues found that completely shutting off Nav1.7 not only made mice pain-free, it cranked up their amount of opioid peptides in nerve cells. These molecules are natural painkillers that help the body moderate pain responses. In these Nav1.7-lacking mice, opioid levels were extremely high, blunting all twinges and throbs. When the researchers gave the mice a drug that blocks those opioids, the animals could feel pain normally. (The opioid-blocking drug, naloxone, treats overdoses of opioid drugs, such as morphine and codeine.)

Even more promising, Wood and colleagues saw the same result in a person. The test subject, a 39-year-old woman with a rare mutation that shuts off Nav1.7, had been pain-free all her life. But, when the researchers gave her a dose of the opioid-blocking naloxone, she felt pain for the first time—the sting of a tiny laser. She was happy to go back to her normal, painless state after the drug wore off, Wood reported. But, she hopes that the drug treatment can be used in children with the pain-free condition to keep them from unknowingly injuring themselves.

Read the entire article here.

tD, Technica

Pain Ray

We humans are capable of the most sublime creations, from soaring literary inventions to intensely moving music and gorgeous works of visual art. This stands in stark and paradoxical contrast to our range of inventions that enable efficient mass destruction, torture and death. The latest in this sad catalog of human tools of terror is the “pain ray”, otherwise known by its military euphemism as an Active Denial weapon. The good news is that it only delivers intense pain, rather than death. How inventive we humans really are — we should be so proud.

[tube]J1w4g2vr7B4[/tube]

From the New Scientist:

THE pain, when it comes, is unbearable. At first it’s comparable to a hairdryer blast on the skin. But within a couple of seconds, most of the body surface feels roasted to an excruciating degree. Nobody has ever resisted it: the deep-rooted instinct to writhe and escape is too strong.

The source of this pain is an entirely new type of weapon, originally developed in secret by the US military – and now ready for use. It is a genuine pain ray, designed to subdue people in war zones, prisons and riots. Its name is Active Denial. In the last decade, no other non-lethal weapon has had as much research and testing, and some $120 million has already been spent on development in the US.

Many want to shelve this pain ray before it is fired for real but the argument is far from cut and dried. Active Denial’s supporters claim that its introduction will save lives: the chances of serious injury are tiny, they claim, and it causes less harm than tasers, rubber bullets or batons. It is a persuasive argument. Until, that is, you bring the dark side of human nature into the equation.

The idea for Active Denial can be traced back to research on the effects of radar on biological tissue. Since the 1940s, researchers have known that the microwave radiation produced by radar devices at certain frequencies could heat the skin of bystanders. But attempts to use such microwave energy as a non-lethal weapon only began in the late 1980s, in secret, at the Air Force Research Laboratory (AFRL) at Kirtland Air Force Base in Albuquerque, New Mexico.

The first question facing the AFRL researchers was whether microwaves could trigger pain without causing skin damage. Radiation equivalent to that used in oven microwaves, for example, was out of the question since it penetrates deep into objects, and causes cells to break down within seconds.

The AFRL team found that the key was to use millimetre waves, very-short-wavelength microwaves, with a frequency of about 95 gigahertz. By conducting tests on human volunteers, they discovered that these waves would penetrate only the outer 0.4 millimetres of skin, because they are absorbed by water in surface tissue. So long as the beam power was capped – keeping the energy per square centimetre of skin below a certain level – the tissue temperature would not exceed 55 °C, which is just below the threshold for damaging cells (Bioelectromagnetics, vol 18, p 403).

The sensation, however, was extremely painful, because the outer skin holds a type of pain receptor called thermal nociceptors. These respond rapidly to threats and trigger reflexive “repel” reactions when stimulated (see diagram).

To build a weapon, the next step was to produce a high-power beam capable of reaching hundreds of metres. At the time, it was possible to beam longer-wavelength microwaves over great distances – as with radar systems – but it was not feasible to use the same underlying technology to produce millimetre waves.

Working with the AFRL, the military contractor Raytheon Company, based in Waltham, Massachusetts, built a prototype with a key bit of hardware: a gyrotron, a device for amplifying millimetre microwaves. Gyrotrons generate a rotating ring of electrons, held in a magnetic field by powerful cryogenically cooled superconducting magnets. The frequency at which these electrons rotate matches the frequency of millimetre microwaves, causing a resonating effect. The souped-up millimetre waves then pass to an antenna, which fires the beam.

The first working prototype of the Active Denial weapon, dubbed “System 0”, was completed in 2000. At 7.5 tonnes, it was too big to be easily transported. A few years later, it was followed by mobile versions that could be carried on heavy vehicles.

Today’s Active Denial device, designed for military use, looks similar to a large, flat satellite dish mounted on a truck. The microwave beam it produces has a diameter of about 2 metres and can reach targets several hundred metres away. It fires in bursts of about 3 to 5 seconds.

Those who have been at the wrong end of the beam report that the pain is impossible to resist. “You might think you can withstand getting blasted. Your body disagrees quite strongly,” says Spencer Ackerman, a reporter for Wired magazine’s blog, Danger Room. He stood in the beam at an event arranged for the media last year. “One second my shoulder and upper chest were at a crisp, early-spring outdoor temperature on a Virginia field. Literally the next second, they felt like they were roasted, with what can be likened to a super-hot tingling feeling. The sensation causes your nerves to take control of your feeble consciousness, so it wasn’t like I thought getting out of the way of the beam was a good idea – I did what my body told me to do.” There’s also little chance of shielding yourself; the waves penetrate clothing.

Read the entire article here.

Related video courtesy of CBS 60 Minutes.

BigBang

Women and Pain

New research suggests that women feel pain more intensely than men.

[div class=attrib]From Scientific American:[end-div]

When a woman falls ill, her pain may be more intense than a man’s, a new study suggests.

Across a number of different diseases, including diabetes, arthritis and certain respiratory infections, women in the study reported feeling more pain than men, the researchers said.

The study is one of the largest to examine sex differences in human pain perception. The results are in line with earlier findings, and reveal that sex differences in pain sensitivity may be present in many more diseases than previously thought.

Because pain is subjective, the researchers can’t know for sure whether women, in fact, experience more pain than men. A number of factors, including a person’s mood and whether they take pain medication, likely influence how much pain they say they’re in.

…

In all, the researchers assessed sex differences in reported pain for more than 250 diseases and conditions.

For almost every diagnosis, women reported higher average pain scores than men. Women’s scores were, on average, 20 percent higher than men’s scores, according to the study.

Women with lower back pain, and knee and leg strain consistently reported higher scores than men. Women also reported feeling more pain in the neck (for conditions such as torticollis, in which the neck muscles twist or spasm) and sinuses (during sinus infections) than did men, a result not found by previous research.

…

It could be that women assign different numbers to the level of pain they perceive compared with men, said Roger B. Fillingim, a pain researcher at the University of Florida College of Dentistry, who was not involved with the new study.

But the study was large, and the findings are backed up by previous work, Fillingim said.

“I think the most [simple] explanation is that women are indeed experiencing higher levels of pain than men,” Fillingim said.

The reason for this is not known, Fillingim said. Past research suggests a number of factors contribute to perceptions of pain level, including hormones, genetics and psychological factors, which may vary between men and women, Fillingim said. It’s also possible the pain systems work differently in men and women, or women experience more severe forms of disease than men, he said.

[div class=attrib]Read the entire article here.[end-div]

[div class]Image courtesy of CNN.[end-div]