Day: 08/04/2014

Seattle scientists seek an Ebola cure .

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Seattle scientists working on an Ebola cure say the growing outbreak in West Africa lends urgency to their mission.

“To see how fast it’s spreading is incredible,” said University of Washington immunologist Michael Gale Jr. “It shows how dire the need is for antiviral therapy.”

Gale and colleagues at Kineta, a Seattle biotech company, have identified compounds that stop the spread of Ebola and other viruses in laboratory experiments on human cells.

Another local lab, headed by UW microbiologistMichael Katze, is using genetic analysis to understand how some individuals survive the deadly infection and to screen existing drugs for Ebola-fighting ability.

Katze and his team have also helped analyze the body’s response to an experimental Ebola vaccine that proved highly effective in monkeys.

Neither Seattle lab is close to bringing a drug to market, but researchers say the outlook is promising — at least from a scientific perspective.

The biggest hurdles are likely to be economic.

Despite the deaths of more than 700 people in recent weeks, Ebola remains a very rare disease, concentrated in some of the world’s poorest countries, Gale pointed out.

“There’s no money in it,” he said. “American pharmaceutical companies won’t touch anything unless there’s at least a billion-dollar market potential.”

Gale hopes to avoid that pitfall by developing treatments that are effective against a wide array of viruses in addition to Ebola — including flu, West Nile virus, dengue fever and possibly even the common cold.

His team is sharing in a five-year, $8.1 million federal grant to identify compounds that rev up the natural infection-fighting ability of cells, allowing them to repel many types of viruses.

In earlier work, Gale identified an enzyme that is key to activating what’s called the innate immune system — the body’s first-line defense against outside invaders.

The enzyme “turns on literally hundreds of genes that fight off viral infection,” he said.

Some viruses, like Ebola, have devised ways to dial down that enzyme, explained Shawn Iadonato, chief scientific officer for Kineta.

At the company’s South Lake Union lab, workers screened more than 100,000 chemical compounds for the ability to dial the enzyme up. They identified 20 promising candidates, three of which stood out in follow-up tests.

No labs in Seattle are equipped or approved to work with Ebola virus, so those tests are conducted at a University of Texas facility in Galveston. “There’s a special building with three-foot-thick concrete walls, negative pressure, Pine-Sol showers, all that kind of stuff,” Gale said. Researchers who handle the virus wear respirators and full protective gear.

The next step in the project is to see if the compounds work as well in monkeys as they do in test tubes, Gale said.

The difficulty of conducting human tests with a disease as deadly as Ebola has stalled progress on other promising treatments, including vaccines, said Angela Rasmussen, a UW researcher who works with Katze.

She and her colleagues have developed strains of laboratory mice that mimic human populations in terms of their genetic variability. When the mice are infected with Ebola in experiments at the federalRocky Mountain Laboratories in Montana, the animals exhibit the same range of symptoms as infected people, including hemorrhage and liver failure.

Most of the mice die. But about 20 percent get sick, lose weight — and then recover.

“That’s what we see in human outbreaks,” Rasmussen said. “Some people can survive, perhaps because they have some genetic trait or immunity.”

By analyzing the mouse genetics in detail and comparing it with the animals’ symptoms and outcomes, the scientists hope to figure out what allows some individuals to recover.

They’re also screening drugs already on the market, to see if they might prove useful. For example, the Ebola virus is known to piggyback into cells on cholesterol molecules, so it’s possible cholesterol drugs could provide some protection.

Though the prospects are good that treatments can be developed, not many U.S. labs are focused on Ebola, Iadonato said. Only a handful are working on broad-spectrum antivirals.

Much of the funding comes under the umbrella of biodefense, out of concern that the Ebola virus could be used as a weapon.

Considering this year’s record-breaking number of cases, the National Institutes of Health decided to fast-track initial human trials on a promising vaccine that worked well in monkeys. But even if the vaccine proves safe and effective, approval wouldn’t come in time to help stem the current outbreak.

Rasmussen, who has assisted in studies on another promising vaccine, would like to see the process accelerated even more.

“This is an emergency situation where peoples’ lives are at stake,” she said. “It’s a terrible human cost, and it’s a terrible way to die.”

NASA’s Top 10 Gamma-Ray Sources in the Universe .

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Gamma-rays are the highest-energy form of light in the universe. Some are generated by transient events, such as solar flares and the huge star explosions known as supernovas. Others are produced by steady sources like the supermassive black holes at the hearts of galaxies.

NASA’s Fermi Gamma-ray Space Telescope has been mapping out the high-energy sky since its June 2008 launch. Earlier this year, the Fermi team released its second catalog of sources detected by the instrument’s Large Area Telescope (LAT), producing an inventory of 1,873 objects shining in gamma-ray light.

Fermi scientists recently compiled a “top 10 list” to mark the occasion, and to highlight the diversity of gamma-ray sources. Five of the sources on the list are found within our own Milky Way, while the other five reside in distant galaxies.

Fermi’s top five sources within our galaxy are:

1. The Crab Nebula: The famous Crab Nebula, located in the constellation Taurus, is the wreckage of an exploded star whose light reached Earth in 1054. Located 6,500 light-years away, the Crab is one of the most-studied objects in the sky. At the heart of an expanding gas cloud lies what’s left of the original star’s core, a super-dense neutron star (also called a pulsar) that spins 30 times per second. Until recently, all of the Crab’s high-energy emissions were thought to be the result of physical processes near the pulsar that tapped into this rapid spin.

For decades, most astronomers regarded the Crab Nebula as a super-steady beacon at X-ray energies. But data from several orbiting instruments — including Fermi’s Gamma-ray Burst Monitor — now show unexpected variations. Astronomers have demonstrated that since 2008, the nebula has faded by 7 percent at high energies, a reduction likely tied to the environment around its central neutron star.

Since 2007, Fermi and the Italian Space Agency’s AGILE satellite have detected several short-lived gamma-ray flares at energies hundreds of times higher than the nebula’s observed X-ray variations. In April, the satellites detected two of the most powerful gamma-ray flares yet recorded.

To account for these “superflares,” scientists say that electrons near the pulsar must be accelerated to energies a thousand trillion times greater than that of visible light. That’s far beyond what can be achieved by the Large Hadron Collider near Geneva, Switzerland, now the most powerful particle accelerator on Earth.

Fermi’s LAT mapped GeV-gamma-ray emission (magenta) from the W44 supernova remnant. The features clearly align with filaments detectable in other wavelengths. This composite merges X-rays (blue) from the Germany-led ROSAT mission, infrared (red) from NASA’s Spitzer Space Telescope, and radio (orange) from the NRAO’s Very Large Array near Socorro, N.M.
Credit: NASA/DOE/Fermi LAT Collaboration, ROSAT, JPL-Caltech, and NRAO/AUI

  1. W44:Another interesting supernova remnant detected by Fermi is W44. Thought to be about 20,000 years old — middle-aged for a such a structure — W44 is located 9,800 light-years away in the constellation Aquila.

The LAT not only detects this W44, it actually reveals super-energetic gamma-rays coming from places where the remnant’s expanding shock wave is known to be interacting with cold, dense gas clouds.

Such observations are important in solving a long-standing problem in astrophysics: the origin of cosmic rays. Cosmic rays are particles, primarily protons, that move through space at nearly the speed of light. Magnetic fields deflect the particles as they race across the galaxy, and this interaction scrambles their path and masks their origins.

Scientists can’t say for sure where the highest-energy cosmic rays come from, but they regard supernova remnants as perhaps their likliest origin.

In 1949, the Fermi telescope’s namesake, physicist Enrico Fermi, suggested that the highest-energy cosmic rays were accelerated in the magnetic fields of gas clouds. In the decades that followed, astronomers showed that the magnetic fields in the expanding shock wave of a supernova remnant are just about the best location for this process to work.

So far, LAT observations of W44 and several other remnants strongly suggest that the gamma-ray emission arises from accelerated protons as they collide with gas atoms.

3. V407 Cygni: V407 Cygni is a so-called symbiotic binary system — one that contains a compact white dwarf and a red giant star that has swollen to about 500 times the size of the sun.

V407 Cyni lies about 9,000 light-years away in the constellation Cygnus. The system occasionally flares up when gas from the red giant accumulates on the dwarf’s surface and eventually explodes. This event is sometimes called a nova (after a Latin term meaning “new star”).

When the system’s most recent eruption occurred in March 2010, Fermi’s LAT surprised many scientists by detecting the nova as a brilliant source. Scientists didn’t expect that this type of outburst had the power to produce high-energy gamma-rays.

4. Pulsar PSR J0101-6422: Pulsars — rapidly rotating neutron stars — constitute about 6 percent of the new catalog. In some cases the LAT can detect gamma-ray pulses directly, but in many cases pulses were first found at radio wavelengths based on suspicions that a faint LAT source might be a pulsar.

PSR J0101-6422 is located in the southern constellation of Tucana, its quirky name reflecting its position in the sky.

The Fermi team originally took notice of the object as a fairly bright but unidentified gamma-ray source in an earlier LAT catalog. Because the distribution of gamma-ray energies in the source resembled what is normally seen in pulsars, radio astronomers in Australia took a look at it using their Parkes radio telescope.

Pulsars are neutron stars, compact objects packing more mass than the sun’s into a sphere roughly the size of Washington, D.C. Lighthouse-like beams of radiation powered by the pulsar’s rapid rotation and strong magnetic field sweep across the sky with every spin, and astronomers can detect these beams if they happen to sweep toward Earth.

The Parkes study found radio signals from a pulsar rotating at nearly 400 times a second — comparable to the spin of a kitchen blender — at the same position as the unknown Fermi source. With this information, the LAT team was able to discover that PSR J0101-6422 also blinks in gamma-rays at the same incredible rate.

5. 2FGL J0359.5+5410: Fermi scientists don’t know what to make of this source, which is located in the constellation Camelopardalis. It resides near the populous midplane of our galaxy, which increases the chance that it’s actually an object in the Milky Way.

While its gamma-ray spectrum resembles that of a pulsar, pulsations have not been detected, and it isn’t associated with a known object at other wavelengths.

The top five sources beyond the Milky Way are:

This radio, optical and gamma-ray composite illustrates the full extent of Cen A’s vast radio-emitting lobes. Radio data (orange) reveal that the structures span more than 1.4 million light-years, and Fermi’s LAT data (purple) show that they also emit gamma rays.
Credit: NASA/DOE/Fermi LAT Collaboration, Capella Observatory, and Ilana Feain, Tim Cornwell, and Ron Ekers (CSIRO/ATNF), R. Morganti (ASTRON), and N. Junkes (MPIfR)

  1. Centaurus A:The giant elliptical galaxy NGC 5128 is located 12 million light-years away in the southern constellation Centaurus. One of the closest active galaxies, it hosts the bright radio source designated Cen A. Much of the radio emission arises from lobes of gas a million light-years wide, which have been hurled out by the supermassive black hole at the galaxy’s center.

Fermi’s LAT detects high-energy gamma-rays from an extended region around the galaxy that corresponds to the radio-emitting lobes. The radio emission comes from fast-moving particles. When a lower-energy photon collides with one of these particles, the photon receives a kick that boosts its energy into the gamma-ray regime.

It’s a process that sounds more like billiards than astrophysics, but Fermi’s LAT shows that it’s happening in Cen A.

Our neighboring galaxy, Andromeda, also goes by the names Messier 31 or M31. Here, it is captured in full in this new image by WISE.
Credit: NASA/JPL-Caltech/UCLA

  1. The Andromeda Galaxy (M31):At a distance of 2.5 million light-years, theAndromeda Galaxy is the nearest spiral galaxy to us, one of similar size and structure as our own Milky Way. Easily visible to the naked eye in a dark sky, it’s also a favorite target of sky gazers.

The LAT team expected to detect M31 because it’s so similar to our own galaxy, which sports a bright band of diffuse emission that creates the most prominent feature in the gamma-ray sky. These gamma-rays are mostly produced when high-energy cosmic rays smash into the gas between stars.

“It took two years of LAT observations to detect M31,” Jürgen Knödlseder at the Research Institute for Astrophysics and Planetology in Toulouse, France, said in a statement. Currently a visiting scientist at the SLAC National Accelerator Laboratory in California, he worked on the M31 study.

“We concluded that the Andromeda Galaxy has fewer cosmic rays than our own Milky Way, probably because M31 forms stars — including those that die as supernovae, which help produce cosmic rays —more slowly than our galaxy,” Knödlseder added.

 

  1. The Cigar Galaxy (M82):What works for the Andromeda Galaxy works even better for M82, a so-called starburst galaxy that is also a favorite of amateur astronomers. M82 is located 12 million light-years away in the constellation Ursa Major.

M82’s central region forms young stars at a rate some 10 times higher than the Milky Way does, activity that also guarantees a high rate of supernovae as the most short-lived stars come to explosive ends.

Eventually, M82’s superpowered star formation will subside as the gas needed to make new stars is consumed, but that may be tens of millions of years in the future. For now, it’s a bright source of gamma-rays for Fermi.

  1. Blazar PKS 0537-286: At the core of an active galaxy is a massive black hole that drives jets of particles moving near the speed of light. Astronomers call the galaxy a blazar when one of these jets is pointed our way — the best view for seeing dramatic flares as conditions change within the jet.

    PKS 0537-286 is a variable blazar in the constellation Leo and the second most distant LAT object. Astronomers have determined that the galaxy lies more than 11.7 billion light-years away.

The blazar is the farthest active galaxy in the Fermi catalog to show variability. Astronomers are witnessing changes in the jet powered by this galaxy’s supermassive black hole that occurred when the universe was just 2 billion years old (it is now about 13.7 billion years old).

  1. 2FGL J1305.0+1152: The last item is another mystery object, one located in the constellation Virgo and high above our galaxy’s midplane. It remains faint even after two years of LAT observations.

One clue to classifying these objects lies in their gamma-ray spectrum — that is, the relative number of gamma-rays seen at different energies. At some energy, the spectra of many objects display what astronomers call a “spectral break,” a greater-than-expected drop-off in the number of gamma-rays seen at increasing energies.

If this object were a pulsar, it would show a fast cutoff at higher energies. Many blazars exhibit much more gradual cutoffs. But 2FGL J1305.0+1152 shows no evidence of a spectral break at all, leaving its nature a true mystery — for now, anyway.

 

Carpal Tunnel: Best Ways to Address Your Pain, Tingling.

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If you spend a lot of time at a computer or working with your hands, you might be tempted to ignore tingling and numbness in your wrist and fingers.

But you shouldn’t, says orthopaedic surgeon Steve Maschke, MD, because frequent burning, tingling or itching in the palm of your fingers can progress and become more painful over time. It’s likely that carpal tunnel syndrome is the culprit, as a key nerve in your wrist becomes compressed.

“An early sign is waking up with a tingling sensation in your hands,” Dr. Maschke says. “If you have symptoms, it’s important to see a doctor early.”

If not addressed, carpal tunnel can cause you to lose grip strength and can even result in wasting away of muscles in the base of the thumb.

What’s happening to the median nerve

The carpal tunnel is a narrow passageway at the base of your hand where tendons and nerves, including the median nerve, pass through. The median nerve controls sensation to the palm side of the thumb and the index, middle, and ring finger.

When the tendons are inflamed or the passage becomes narrow for any other reason, your median nerve becomes compressed, causing pain and numbness in the hand, wrist and arm.

A combination of factors may be involved, including:

Genetics – Some people may simply have a genetic predisposition to carpal tunnel. “It is an issue of a size mismatch,” Dr. Maschke says. “The carpal tunnel is a tight space, and it’s a smaller channel in some people than others.” This may be why women, who tend to have smaller carpal tunnels, are affected three times more often than men.

Repetitive vibration – Research shows that repetitive vibration in particular, but also  repetition, wrist flexion and powerful grip, all raise the risk for carpal tunnel. “Think of what you’d feel when using a jack hammer or other piece of vibrating machinery,” Dr. Maschke says.

Underlying health conditions – These include pregnancy and menopause, which can cause fluid retention. Diabetes, obesity, thyroid problems and rheumatoid arthritis also may cause the median nerve to become compressed.

Injury – Trauma or injury to the to the wrist, such as a sprain or break, can cause swelling – resulting in tingling and pain. Mechanical problems in the wrist also can cause these issues.

Lifestyle factors — Using a keyboard heavily, sleeping with your wrist flexed, or performing tasks that involve repetitive motions with your hands and wrists or pressure on your palms can exacerbate carpal tunnel symptoms.

Address early symptoms

It’s important to talk to your doctor about your symptoms, especially if they have progressed.

However, if you’re in good health and have no neck pain or injury, Dr. Maschke  says it’s safe to take a couple weeks to try these suggestions first:

  • Use a brace –Try wearing braces to keep your wrists in a neutral position at night or while typing or doing other tasks with your hands.
  • Change your work station setup – If you work at a computer, be sure you can sit with your wrists and hands in a neutral position. If you work on an assembly line, study the movements you make to see if you can ease stress on the wrists and hands. Also talk to your supervisor about ways to vary your activities so they are less repetitive.
  • Take over-the-counter pain meds – This may include aspirin, ibuprofen or other nonprescription pain relievers for people with mild or intermittent pain.
  • Deal with health issues – Lose weight if you need to. Manage diabetes if you have it. “And if you smoke, quit,” Dr. Maschke says. “Smoking seems to exacerbate symptoms.”

Don’t assume every symptom in your hands is caused by carpal tunnel syndrome, Dr. Maschke says. If symptoms don’t improve quickly, make an appointment to see your doctor.

Ebola around the world.

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Fareed speaks with Sanjay Gupta, CNN’s chief medical correspondent, about the recent outbreak of Ebola. Watch the full interview on “Fareed Zakaria GPS,” this Sunday at 10 a.m. and 1 p.m. ET on CNN.

Sanjay, how has this been blocked in the past? Why does this seem unprecedented? Is there something different right now?

You know, in a morbid way, it’s because it killed so quickly – it would just burn out. You imagine these remote villages. People weren’t moving around as quickly. And the Ebola virus – they would die and before they could start to spread it…it’s awful to think about, but that’s what was happening.

Now, you have a more mobile group. You have more roads between some of these smaller villages, such as in Guinea, where this originated, and the capital city of Conakry. There are roads. There are all these good passageways now back and forth. And so I think that part of it is certainly contributing. There’s also this idea that there’s a mistrust – I think a little bit of distrust, maybe – even of health care professionals. In part, that’s fueled by the fact that there’s no good anti-viral, there’s no good vaccine. So we need to see health care workers show up, they’re not offering some panacea to what is happening here.

And so there’s not a lot of trust. And a lot of the people who are getting infected aren’t hearing the right messages.  And you also have several epidemics sort of starting in different points almost simultaneously now. Usually, it was one place you could target.

Sanjay, how are we going to control the spread? How does one track whether people have Ebola? You think about, as you say, there are roads. There are also trains. There are also planes now. People can get on flights from Liberia, from Sierra Leone. How do we handle this?

Well, I think we’re going to hear at some point – I don’t know if it’s during this outbreak or a future one – we are going to hear about patients with Ebola showing up in other countries in the Western Hemisphere. I can’t imagine that not happening, having seen how it all works. And keep in mind, between the time of exposure to the virus and the time someone gets sick, it could be as long as 21 days. It can travel all over the world, obviously, during that time.

I think if there’s any good news in this, it’s when you think about countries like the United States, Britain, who are having high level discussions on this topic, they are in a much better position to be able to control this. First of all, they could isolate the patient quite quickly, provide fluids and blood clotting factors to try and provide what is called supportive therapy and prevent these patients with the virus becoming epidemics or the source of epidemics.

So I think it’s going to happen. We’re going to see Ebola around the world. But I think it’s not going to turn into lots of mini outbreaks.​

 

Nanoscale details of electrochemical reactions in electric vehicle battery materials.

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Using a new method to track the electrochemical reactions in a common electric vehicle battery material under operating conditions, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have revealed new insight into why fast charging inhibits this material’s performance. The study also provides the first direct experimental evidence to support a particular model of the electrochemical reaction. The results, published August 4, 2014, in Nature Communications, could provide guidance to inform battery makers’ efforts to optimize materials for faster-charging batteries with higher capacity.

“Our work was focused on developing a method to track structural and electrochemical changes at the nanoscale as the battery material was charging,” said Brookhaven physicist Jun Wang, who led the research. Her group was particularly interested in chemically mapping what happens in lithium -a material commonly used in the cathode, or positive electrode, of electrical vehicle batteries-as the battery charged. “We wanted to catch and monitor the phase transformation that takes place in the cathode as lithium ions move from the cathode to the anode,” she said.

Getting as many lithium ions as possible to move from cathode to anode through this process, known as delithiation, is the key to recharging the battery to its fullest capacity so it will be able to provide power for the longest possible period of time. Understanding the subtle details of why that doesn’t always happen could ultimately lead to ways to improve battery performance, enabling electric vehicles to travel farther before needing to be recharged.

X-ray imaging and chemical fingerprinting

Many previous methods used to analyze such battery materials have produced data that average out effects over the entire electrode. These methods lack the spatial resolution needed for chemical mapping or nanoscale imaging, and are likely to overlook possible small-scale effects and local differences within the sample, Wang explained.

To improve upon those methods, the Brookhaven team used a combination of full- field, nanoscale-resolution transmission x-ray microscopy (TXM) and x-ray absorption near-edge spectroscopy (XANES) at the National Synchrotron Light Source (NSLS), a DOE Office of Science User Facility that provides beams of high-intensity x-rays for studies in many areas of science. These x-rays can penetrate the material to produce both high-resolution images and spectroscopic data-a sort of electrochemical “fingerprint” that reveals, pixel by pixel, where lithium ions remain in the material, where they’ve been removed leaving only iron phosphate, and other potentially interesting electrochemical details.

The scientists used these methods to analyze samples made up of multiple nanoscale particles in a real battery electrode under operating conditions (in operando). But because there can be a lot of overlap of particles in these samples, they also conducted the same in operando study using smaller amounts of electrode material than would be found in a typical battery. This allowed them to gain further insight into how the delithiation reaction proceeds within individual particles without overlap. They studied each system (multi-particle and individual particles) under two different charging scenarios-rapid (like you’d get at an electric vehicle recharging station), and slow (used when plugging in your vehicle at home overnight).

Insight into why charging rate matters

These animated images of individual particles, taken while the electrode is charging, show that lithiated (red) and delithiated (green) iron phosphate phases co-exist within individual particles. This finding directly supports a model in which the phase transformation proceeds from one phase to the other without the existence of an intermediate phase.

The detailed images and spectroscopic information reveal unprecedented insight into why fast charging reduces battery capacity. At the fast charging rate, the pixel-by-pixel images show that the transformation from lithiated to delithiated iron phosphate proceeds inhomogeneously. That is, in some regions of the electrode, all the lithium ions are removed leaving only iron phosphate behind, while particles in other areas show no change at all, retaining their lithium ions. Even in the “fully charged” state, some particles retain lithium and the electrode’s capacity is well below the maximum level.

“This is the first time anyone has been able to see that delithiation was happening differently at different spatial locations on an electrode under rapid charging conditions,” Jun Wang said.

Slower charging, in contrast, results in homogeneous delithiation, where lithium iron phosphate particles throughout the electrode gradually change over to pure iron phosphate-and the electrode has a higher capacity.

Implications for better battery design

Scientists have known for a while that slow charging is better for this material, “but people don’t want to charge slowly,” said Jiajun Wang, the lead author of the paper. “Instead, we want to know why fast charging gives lower capacity. Our results offer clues to explain why, and could give industry guidance to help them develop a future fast-charge/high-capacity battery,” he said.

For example, the phase transformation may happen more efficiently in some parts of the electrode than others due to inconsistencies in the physical structure or composition of the electrode-for example, its thickness or how porous it is. “So rather than focusing only on the battery materials’ individual features, manufacturers might want to look at ways to prepare the electrode so that all parts of it are the same, so all particles can be involved in the reaction instead of just some,” he said.

The individual-particle study also detected, for the first time, the coexistence of two distinct phases-lithiated iron phosphate and delithiated, or pure, iron phosphate-within single particles. This finding confirms one model of the delithiation -namely that it proceeds from one phase to the other without the existence of an intermediate phase.

“These discoveries provide the fundamental basis for the development of improved battery materials,” said Jun Wang. “In addition, this work demonstrates the unique capability of applying nanoscale imaging and spectroscopic techniques in understanding with a complex mechanism in real operational conditions.”

The paper notes that this in operando approach could be applied in other fields, such as studies of fuel cells and catalysts, and in environmental and biological sciences.

Future studies using these techniques at NSLS-II-which will produce x-rays 10,000 times brighter than those at NSLS-will have even greater resolution and provide deeper insight into the physical and electrochemical characteristics of these materials, thus making it possible for scientists to further elucidate how those properties affect performance.

Scorpion Envenomation.

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Each year more than a million cases of scorpion envenomation occur worldwide, causing substantial morbidity and, among children, a risk of death. A new brief review discusses the effects and treatment of scorpion envenomation. Every year, more than 1 million cases of scorpion envenomation are reported worldwide. Although the resultant mortality is lower than that from snake envenomation, there is substantial morbidity and, among children, a risk of death.

Clinical Pearls

• What are the general characteristics of scorpion stings?

Most scorpion stings cause localized pain, whereas only an estimated 10% of stings, even from the most dangerous scorpions, result in severe systemic envenomation. Edema, erythema, paresthesias, muscle fasciculations, and numbness may occur at the site of the sting. It is often difficult to see the sting site or to identify inflammation at the site, despite substantial local pain. Most cases of severe envenomation occur in children. Systemic envenomation is characterized by neuromuscular abnormalities resulting from effects on the somatic and cranial nerves, both cholinergic and adrenergic excitation of the autonomic nervous system, pulmonary edema, and cardiac effects.

• What are the autonomic effects of scorpion stings?

Excitation of the autonomic nervous system is characterized by both parasympathetic and sympathetic responses. Parasympathetic, cholinergic effects may include hypersalivation, profuse diaphoresis, lacrimation, miosis, diarrhea, vomiting, bradycardia, hypotension, increased respiratory secretions, and priapism. Sympathetic, adrenergic effects include tachycardia, hypertension, mydriasis, hyperthermia, hyperglycemia, agitation, and restlessness. Whereas most parasympathetic effects tend to occur early, sympathetic effects persist because of the release of catecholamines and are responsible for severe envenomation.

Morning Report Questions

Q: What are possible cardiovascular complications of scorpion envenomation?
A: A range of cardiac conduction abnormalities occur in about one third to one half of patients with systemic envenomation. These effects include atrial tachycardia, ventricular extrasystoles, T-wave inversion, ST-T wave changes, and, less frequently, bundle-branch block. Increased autonomic stimulation caused by increased vagal effects on the heart and sympathetic stimulation are the probable causes of these effects. Hypertension is common and occurs early in response to sympathetic stimulation. Hypotension is less common, occurs with the development of severe envenomation, and often requires intervention with vasopressors and fluid resuscitation. Many factors are at play in the development of hypotension, with cholinergic stimulation causing vasodilation, fluid loss, and myocardial depression. Cardiac dysfunction resulting from catecholamine-induced myocarditis and myocardial ischemia complicates severe envenomation from androctonus, buthus, mesobuthus, and tityus scorpions. This complication may result in pulmonary edema and cardiogenic shock.

Q: What are the principles of treatment for cases of severe scorpion envenomation?
A: The specific treatment is the administration of antivenom combined with symptomatic and supportive treatment, including prazosin and dobutamine in patients with cardiovascular toxic effects and benzodiazepines when there is neuromuscular involvement. Symptoms related to the site of the sting should be managed with appropriate analgesia with acetaminophen and antiinflammatory agents, depending on severity. Once severe envenomation has developed, the administration of antivenom may be less effective, since its primary therapeutic action is to bind toxins; it does not reverse established pathophysiological injury, such as excess levels of catecholamine, pulmonary edema, and cardiogenic shock.

VIEW THIS:  http://www.nejm.org/action/showImage?doi=10.1056/NEJMra1401108&iid=t01