October 13, 2013
Recently, there’s been a bunch of research indicating marijuana isn’t the worst drug in the world—long-term use of it might not harm IQ, and it can serve as an effective way to distract people from chronic pain.
That said, there are plenty of drug users—along with drug counselors and medical professional—seeking ways to aid in kicking the habit. For them, a new finding by researchers from the National Institute on Drug Abuse (NIDA) and elsewhere might be rather interesting.
As documented in a paper published today in Nature Neuroscience, the scientists used a drug to increase levels of the naturally-occurring chemical kynurenic acid in the brains of rats who’d been dosed with marijuana’s active ingredient (THC). When they did that, activity levels driven by the neurotransmitter dopamine, associated with pleasure, went down in key areas of their brains. In a second experiment, when they dosed monkeys who were able to self-medicate with the marijuana ingredient, they voluntarily consumed roughly 80 percent less of it.
In other words, by jacking up levels of kynurenic acid, the drug (with the decidedly user-unfriendly name Ro 61-8048) seems to make marijuana less pleasurable and therefore less psychologically addictive.
“The really interesting finding is that when we looked at behavior, simply increasing kynerenic acid levels totally blocked the abuse potential and the chance of relapse,” said Robert Schwarcz, a neuroscientist at the University of Maryland and co-author of the study. “It’s a totally new approach to affecting THC function.”
Neuroscientists have known for some time that marijuana—along with many other drugs with abuse potential, including nicotine and opiates—induces a feeling of euphoria by increasing levels of dopamine in the brain. Over the past few decades, Schwarcz and others have also discovered that kynurenic acid is crucially involved in the regulation of brain activity driven by dopamine.
Schwarcz, working with researchers at NIDA (which is one of the few facilities in the country that can obtain and use THC in a pure form) and Jack Bergman‘s lab at Harvard (which studies the effects of THC and other drugs on animals), combined these two principles to see how kynurenic acid levels could be manipulated to disrupt marijuana’s pleasure-inducing ability. To do so, they identified that Ro 61-8048 interfered with the chemical pathway kynurenic acid takes through brain cells, creating a metabolic blockage so that kynurenic acid levels artificially rose.
When they dosed rats with this drug, they found that dopamine-driven brain activity in several key reward centers of the brain (such as the nucleus accumbens) no longer surged in lockstep with THC, as it usually does. This confirmed their hypothesis that kynurenic acid can block the same neuron receptors that dopamine usually fits into, rendering it less effective in provoking the reward centers and providing a feeling of euphoria.
Even more intriguing was the behavior they observed in both the rats and monkeys who were given the drug. By pressing levers inside their cages, the animals were able to dose themselves with THC repeatedly over time—and in the first phase of the experiment, they did so at a furious rate, hitting the levers 1.2 times per second.
But when the researchers increased their kynurenic acid levels with Ro 61-8048, they chose to consume about 80 percent less THC. After the drug wore off, and their kynurenic acid levels decreased to normal, they went right back to hitting the THC levers rapidly.
In another experiment, the scientists tested the monkeys’ tendency to relapse. First, they gave them as much THC as they wanted, then slowly dialed down the amount of THC injected with each lever push until it reached zero, leading the monkeys to eventually stop hitting the levers. Then, they gave the monkeys a small unprompted injection of THC, prompting them to start hitting the levers furiously again. But when the monkeys were dosed with Ro 61-8048 before the injection far fewer relapsed, essentially ignoring the levers—presumably because the squirt of THC didn’t provoke the same level of pleasure.
Dopamine is involved in the pleasure that lots of different drugs generate in the brain, so administering Ro 61-8048 could serve the same anti-addictive purpose when used with other drugs, the authors note. ”Currently, we’re doing some experiments with nicotine abuse, and there’s some very interesting preliminary data indicating it may work the same way,” Schwarcz said.
He cautions, though, that it’ll likely be years before this approach leads to an FDA-approved addiction treatment, in part because of the complexity of the brain and the way various neurotransmitters affect it. “Too much dopamine is bad for us, but too little dopamine is bad for us too,” he said. “You want homeostasis, so we have to be careful not to decrease dopamine levels too much.” But in the long-term, if scientists figure out how to safely increase kynurenic acid levels to limit dopamine’s effectiveness, people who suffer from addiction may have a new option when trying to wean themselves off their drugs of choice.
October 10, 2013
The star GD61 is a white dwarf. As such, it’s insanely dense—similar in diameter to Earth, but with a mass roughly that of the Sun, so that a teaspoon of it is estimated to weigh about 5.5 tons. All things considered, it’s not a particularly promising stellar locale to find evidence of life.
But a new analysis of the debris surrounding the star suggests that, long ago, GD61 may have provided a much more hospitable environment. As part of a study published today in Science, scientists found that the crushed rock and dust near the star were once part of a small planet or asteroid made up of 26 precent water by volume. The discovery is the first time we’ve found water in a rocky, Earth-like planetary body (as opposed to a gas giant) in another star system.
“Those two ingredients—a rocky surface and water—are key in the hunt for habitable planets,” Boris Gänsicke of the University of Warwick in the UK, one of the study’s authors, said in a press statement. “So it’s very exciting to find them together for the first time outside our solar system.”
Why was water found in such a seemingly unhospitable place? Because once upon a time, GD61 wasn’t so different from our Sun, scientists speculate. But roughly 200 million years ago, when it exhausted its supply of fuel and could no longer sustain fusion reactions, its outer layers were blown out as part of a nebula, and its inner core collapsed inward, forming a white dwarf. (Incidentally, this fate will befall an estimated 97 percent of the stars in the Milky Way, including the Sun.)
When that happened, the tiny planet or asteroid in question—along with all the other bodies orbiting GD61—were violently knocked out of orbit, sucked inward, and ripped apart by the force of the star’s gravity. The clouds of dust, broken rock and water that the scientists recently discovered near the star are the remnants of these planets.
Even in its heyday, the watery body was probably still very small—perhaps comparable in size to our solar system’s dwarf planet Ceres, which orbits in the asteroid belt and is about .015 percent the mass of Earth. Additionally, like Ceres, the ancient planet or asteroid was extremely water-rich (26 percent water, far more than Earth’s .023 percent), and this water was similarly constituted as ice locked within a rocky crust.
To find all this out, the group of scientists (which also includes Jay Farihi of the University of Cambridge and Detlev Koester of the University of Kiel) used observations from two sources: a spectrograph on board the Hubble Space Telescope, through which they obtained data on ultraviolet light emitted by GD61, and a telescope at the W.M. Keck Observatory on Mauna Kea on Hawaii.
By looking at the light emitted from the star, which glows in certain patterns depending on the chemical signatures of gases present, they were able to determine the proportions of a number of elements (including oxygen, magnesium, aluminum, silicon, calcium and iron) contained within the cloud of dust that surrounds it. Using computer simulations of this stellar atmosphere, they were able to rule out a number of alternate possibilities that could have accounted for the abundance of oxygen, leaving only the explanation that it was brought there in water form.
Based on the amount of water and rocky minerals detected in the star’s atmosphere—and assuming it all came from one body—scientists speculate that the small planet or asteroid ripped up by the white dwarf was at least 56 miles in diameter, but perhaps much larger.
Although the star certainly isn’t home to any life at the moment due to its relatively cold temperature, the finding makes it seem more likely that other exoplanets contain water, which is necessary for life as we know it. Many scientists have speculated that small planets and asteroids like Ceres delivered water to Earth in the first place, so finding evidence of a watery body like this in another star system raises the possibility that the same process may have brought water to an Earth-sized planet elsewhere too.
“The finding of water in a large asteroid means the building blocks of habitable planets existed—and maybe still exist—in the GD 61 system, and likely also around a substantial number of similar parent stars,” Farihi said. “These water-rich building blocks, and the terrestrial planets they build, may in fact be common.”
October 2, 2013
Editor’s Note, Oct. 9: Based on several comments that mentioned that the Josephine Brine Treatment Facility stopped treating fracking wastewater in 2011, we did a bit of digging and found that the treated water downstream from the plant still showed signatures that fresh fracking water had run through it, according to the study’s authors. The post has been revised with this information, along with the fact that treatment does remove a good bit of contamination.
In the state of Pennsylvania, home to the lucrative Marcellus Shale formation, 74 facilities treat wastewater from the process of hydraulic fracturing (a.k.a. “fracking”) for natural gas and release it into streams. There’s no national set of standards that guides this treatment process—the EPA notes that the Clean Water Act’s guidelines were developed before fracking even existed, and that many of the processing plants “are not properly equipped to treat this type of wastewater”—and scientists have conducted relatively little assessment of the wastewater to ensure it’s safe after being treated.
Recently, a group of Duke University scientists decided to do some testing. They contacted the owners of one treatment plant, the Josephine Brine Treatment Facility on Blacklick Creek in Indiana County, Pennsylvania, but, “when we tried to work with them, it was very difficult getting ahold of the right person,” says Avner Vengosh, an Earth scientist from Duke. “Eventually, we just went and tested water right from a public area downstream.”
Their analyses, made on water and sediment samples collected repeatedly over the course of two years, were even more concerning than we’d feared. As published today in the journal Environmental Science and Technology, they found elevated concentrations of the element radium, a highly radioactive substance. The concentrations within sediments in particular were roughly 200 times higher than background levels. In addition, amounts of chloride and bromide in the water were two to ten times greater than normal.
This is despite the fact that treatment actually removes most of the contaminants from the wastewater–including 90 percent of the radium. “Even if, today, you completely stopped disposal of the wastewater,” Vengosh says, there’s enough contamination built up in sediments that “you’d still end up with a place that the U.S. would consider a radioactive waste site.”
In recent years, the use of fracking to extract natural gas from shale formations has boomed in several areas, most notably Pennsylvania’s Marcellus Shale, which has been called “the Saudi Arabia of natural gas.” The process involves injecting mix of water, sand and proprietary chemicals deep into rock at high pressure, causing the rock to fracture and allowing methane gas to seep upward for extraction.
Much of the concern over fracking has related to the seepage of these chemicals or methane from drilling wells into groundwater or the fact that high-pressure injection can trigger earthquakes, but the wastewater recently tested presents a separate, largely overlooked problem.
Between 10 and 40 percent of fluid sent down during fracking resurfaces, carrying contaminants with it. Some of these contaminants may be present in the fracking water to begin with. But others are leached into the fracking water from groundwater trapped in the rock it fractures.
Radium, naturally present in the shales that house natural gas, falls into the latter category—as the shale is shattered to extract the gas, groundwater trapped within the shale, rich in concentrations of the radioactive element, is freed and infiltrates the fracking wastewater.
Other states require this wastewater to be pumped back down into underground deposit wells sandwiched between impermeable layers of rock, but because Pennsylvania has few of these cavities, it allows fracking wastewater to be processed by normal wastewater treatment plants and released into rivers.
In 2011, Pennsylvania Department of Environmental Protection (PADEP) issued a recommendation that plants, including Josephine, voluntarily stop treating fracking wastewater. But Jim Efstathiou Jr. at Bloomberg News reports that, even though spokespeople at PADEP and Josephine say that the plant has stopped treating fracking wastewater, those claims are “contradicted by today’s study, which shows that the Josephine plant continued to treat Marcellus Shale wastewater through the beginning of this year,” according to Vengosh.
“Based on the isotopes that we measured we can see that the effluent that’s coming from Josephine in the last three years, including two months ago, still has the fingerprint of the Marcellus,” Vengosh told Efsathiou.
The treatment plants, many scientists note, are not designed to handle the radioactive elements present in the wastewater. Neither are they required to test their effluent for radioactive elements. As a result, many researchers have suspected that the barely-studied water they release into local streams retains significant levels of radioactivity.
This new work confirms that suspicion for at least one plant—which as about an hour east of Pittsburgh, and releases effluent into the watershed that supplies the city’s drinking water—and Vengosh believes that the findings would likely be similar for many of the other facilities in Pennsylvania. Especially concerning is the fact that, apart from in the water, the team found high levels of radioactivity accumulating on the sediments at the bottom of the stream over time. Radium has a half-life of 1600 years, so unless these sediments are removed, they’ll keep releasing radiation into the water for an extremely long period.
In addition, the high levels of bromide found in the wastewater is a concern, because even in slight quantities, the compound can trigger the formation of a toxic class of chemicals called halomethanes when it’s combined with chlorine. This is a problem because in rural areas, many residents treat well water by chlorinating it.
The study—which is part of a larger Duke project studying the effect of fracking on water—doesn’t show that fracking is inherently unsafe, but does show that without proper controls, the wastewater being dumped into the environment daily represents a very real danger for local residents.
Vengosh notes that there are better methods of treating fracking wastewater (he points to the plants operated by Eureka Resources as a model for adequately removing radioactivity), but these are more expensive to operate. But currently, without the push of federal regulations, companies looking to dispose of wastewater have no incentive to pay for this type of solution.
September 26, 2013
Some 46 Martian days after landing on Mars in August 2012, after traveling nearly 1,000 feet from its landing site, Curiosity came upon a pyramid-shaped rock, roughly 20 inches tall. Researchers had been looking for a rock to use for calibrating a number of the rover’s high-tech instruments, and as principal investigator Roger Wiens said at a press conference at the time, “It was the first good-size rock that we found along the way.”
For the first time, scientists used the rover’s Hand Lens Imager (which takes ultra-high resolution photos of a rock’s surface) and the Alpha Particle X-ray Spectrometer (which bombards a rock with alpha particles and X-rays, kicking off electrons in patterns that allow scientists to identify the elements locked within it). They also used the ChemCam, a device that fires a laser at a rock and measures the abundances of elements vaporized.
Curiosity, for its part, commemorated the event with a pithy tweet:
I did a science! 1st contact science on rock target Jake. Here’s an action shot pic.twitter.com/pzcgH6Bk
— Curiosity Rover (@MarsCuriosity) September 22, 2012
A year later, the Curiosity team’s analysis of the data collected by these instruments, published today in Science, shows that they made a pretty lucky choice in finding a rock to start with. The rock, dubbed “Jake_M” (after engineer Jake Matijevic, who died a few days after Curiosity touched down), is unlike any rock previously found on Mars—and its composition intriguingly suggests that it formed after molten rock cooled quickly in the presence of underground water.
The new discovery was published as part of a special series of papers in Science that describe the initial geologic data collected by Curiosity’s full suite of scientific instrumentation. One of the other significant findings is a chemical analysis of a scoop of Martian soil—heated to 835 degrees Celsius inside the Sample Analysis at Mars instrument mechanism—showing that it contains between 1.5 and 3 percent water by weight, a level higher than scientists expected.
But what’s most exciting about the series of findings is the surprising chemical analysis of Jake_M. The researchers determined that it is likely igneous (formed by the solidification of magma) and, unlike any other igneous rocks previously found on Mars, has a mineral composition most similar to a class of basaltic rocks on Earth called mugearites.
“On Earth, we have a pretty good idea how mugearites and rocks like them are formed,” Martin Fisk, an Oregon State University geologist and co-author of the paper, said in a press statement. “It starts with magma deep within the Earth that crystallizes in the presence of one to two percent water. The crystals settle out of the magma, and what doesn’t crystallize is the mugearite magma, which can eventually make its way to the surface as a volcanic eruption.” This happens most frequently in underground areas where molten rock comes into contact with water—places like mid-ocean rifts and volcanic islands.
The fact that Jake_M closely resembles mugearites indicates that it likely took the same path, forming after other minerals crystallized in the presence of underground water and the remaining minerals were sent to the surface. This would suggest that, at least at some time in the past, Mars contained reserves of underground water.
The analysis is part of a growing body of evidence that Mars was once home to liquid water. Last September, images taken by Curiosity showed geologic features that suggested the one-time presence of flowing water at the surface. Here on Earth, analyses of several meteorites that originated on Mars have also indicated that, at some point long ago, the planet held reserves of liquid water deep underground.
This has scientists and members of the public excited, of course, because (at least as far as we know) water is a necessity for the evolution of life. If Mars was once a water-rich planet, as Curiosity’s findings increasingly suggest, it’s possible that life may have once evolved there long ago—and there may even be organic compounds or other remnants of life waiting to be found by the rover in the future.
September 10, 2013
If, in the midst of a Szechuan pepper-heavy meal, you have the presence of mind to ignore the searing hot pain that fills your mouth, you might notice a more subtle effect of eating the hot peppers: a tingling, numbing sensation that envelops your lips and tongue.
What’s behind this strange phenomenon, scientifically known as paresthesia? Scientists believe that it has something to do with a molecule called hydroxy-alpha-sanshool, naturally present in the peppers.
Research has shown that the molecule interacts with our cell’s receptors differently than capsaicin, the active ingredient in the world’s hottest chili peppers. Capsaicin produces a pure burning sensation by binding to the same sorts of receptors present in our cells that are activated when we’re burned by excessive heat, but the Szechuan peppers’ active chemical appears to act on separate receptors as well, perhaps accounting for the distinctive tingling that can persist for minutes after the burn has gone away.
Now, in a study that required some uncommonly compliant volunteers—they let their lips get brushed with ground Szechuan pepper—researchers found that the peppers produce the tingle by exciting tactile sensors in our lips and mouth. In other words, it seems that apart from tasting the peppers’ spiciness, we feel it too, as though our lips are being physically touched by the chemicals present in the Szechuans.
As part of the study, published today in the Proceedings of the Royal Society B, a group of neuroscientists from University College London gathered 28 people and subjected them to ground Szechuans and small metal vibrating tools. Initially, they ground up the peppers, mixed them with ethanol and water, and brushed them onto the lips of the participants, who reported the level of tingling they felt.
Then, to try figuring the exact frequency of the tingling—a concept that becomes a bit more intuitive if you think of the tingling, or numbness, as the lips being vibrated quickly—they held a small vibrating tool up to the volunteers’ fingers. They could control how fast or slow the tool vibrated, and were asked to set it so that it matched the same feeling as the tingling on their lips. After the Szechuan tingling had time to die down, the vibrating tools were placed on their lips in the same spot, and again the participants could control the vibrating to make it resemble the pepper numbness as closely as possible.
When they looked at the records of the tool’s frequency, they found that the participants consistently set it to vibrate at 50 hertz (another way of saying 50 cycles per second). This consistency across people was telling—specific classes of tactile receptors in our cells are each activated by different frequencies (when touched, they pass along an electric current through nerve fibers, ultimately signaling to the brain that physical contact has occurred), so it supported the idea that touch receptors were involved. Which class of receptor, though, is activated by Szechuan peppers?
The scientists say that frequency of the Szechuan’s numbing sensation fell within the range of vibration typically conveyed by a highly-sensitive type of tactile receptor called Meissner receptors, which cover around 10-80 hertz. Previous work has shown that in human nerve cells cultured in petri dishes, the sanshool molecule caused fibers associated with Meissner receptors to fire, passing along a burst of electricity.
This experiment showed that in the real world, the Szechuans’ active ingredient seems to do the same thing, triggering activity in this set of receptors and causing them to pass along tactile stimuli towards the brain, thereby making our lips feel numb, as though they’ve been vibrated quickly. It’s a strange idea, but not unlike the feeling of spiciness: When you eat the pepper, you’re not actually being burned, but your heat-sensitive receptors are being activated, making it seem that way. In the same way, if you’re daring enough to bite into a Szechuan, the touch receptors in your lips and mouth will be stimulated, and as a result, they’ll go numb in a few minutes.