SOME WARNING SIGNS

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Well, after checking the files, I’ve discovered the one that’s overflowing this week. It’s the one about the ills that plague us all. So off we go to the medicine file for a story about what will get most of us in the end.

MORE COMMON THAN WE BELIEVE

So-called “silent” heart attacks may be much more common than previously believed, according to researchers at Duke University Medical Center. Studies show that each year, nearly 200,000 people in the U.S suffer a heart attack but may not realize it. These “silent” heart attacks aren’t reported because they don’t cause any pain – or at least any pain that patients believe is related to their heart – and they don’t leave behind any telltale irregularities on electrocardiograms (ECGs also called EKGs).

This new research suggests that these heart attacks (now called unrecognized myocardial infarctions, or UMIs) may be happening much more frequently than physicians had suspected. Duke investigators also found that these attacks were associated with a surprisingly high risk of untimely death.

Physicians can usually tell when a heart attack has recently occurred by signature changes on ECGs and in certain blood enzyme levels. But if a heart attack happened in the distant past, physicians rely on the appearance of a specific alteration on an ECG called a Q-wave, which signals the presence of damaged tissue.

This research shows that not all silent heart attacks produce Q-waves on an electrocardiogram. They used something called delayed enhancement cardiovascular magnetic resonance, or DE-CMR, and discovered that this new technique was particularly good at telling damaged tissue from healthy tissue.

Researchers used DE-CMR to examine185 patients suspected of having coronary artery disease but who had no record of any heart attacks. All of them were scheduled to undergo angiography to find out if excess plaque had narrowed or blocked any of their arteries. Investigators followed the patients for two years to see if the presence of any unrecognized non-Q-wave heart attacks were associated with a higher risk of death.

They found that 35 percent of the patients had evidence of a heart attack and that non-Q-wave attacks were three times more common than heart attacks that produced the traditional symptoms. Non-Q-wave attacks were also more common among those with more severe coronary artery disease. In addition, researchers discovered that those who suffered silent heart attacks had an 11-fold higher risk of death from any cause and a 17-fold higher risk of death due to heart problems, when compared to patients who did not have any heart damage.

Right now, there are no specific guidelines about how patients with silent heart attacks should be treated. If they happen to be identified, they’re usually treated similarly to those patients where heart disease has already been documented. Future studies will likely examine how common unrecognized heart attacks are in other patient groups and how they should be treated.

So we still don’t know how to identify these silent heart attacks, but that’s not the case with detecting the effects of stroke.

THE EYES HAVE IT

Researchers at Johns Hopkins and the University of Illinois have found that a simple, one-minute eye movement exam performed at the bedside worked better than an MRI to distinguish new strokes from other less serious disorders in patients complaining of dizziness, nausea and spinning sensations.

The study was of 101 patients, who were already at higher than normal risk of stroke because of factors including high blood pressure or high cholesterol, and were all seen at OSF St. Francis Medical Center in Peoria, Ill.

The project, spearheaded by a Johns Hopkins neurologist in collaboration with colleagues at the University of Illinois in Peoria, found that the quick, extremely low-cost exam caught more strokes than the current gold standard of MRI, suggesting that if further research on broader populations confirms these results, physicians may have a way to improve care and avoid the high costs of MRI in some cases.

Dizziness is a common medical problem, responsible for 2.6 million emergency room visits annually in the United States. While the vast majority of dizziness complaints are caused by benign inner-ear balance problems, about 4 percent are signals of stroke or transient ischemic attack (TIA, a condition that often warns of impending stroke in the coming days or weeks). Because more than half of patients with dizziness who are experiencing strokes show none of the classic stroke symptoms — one-sided weakness, numbness, or speech problems — emergency room physicians are estimated to misdiagnose at least a third of them, losing the chance for quick and effective treatment.

The study of eye movement tests was suggested by previous research showing that people experiencing a stroke have eye-movement alterations that correlate with stroke-damage to various brain areas and that these are distinct from eye-movement alterations seen with benign ear diseases. Some patients, for example, can’t immediately adjust their eye position if their heads are quickly turned to the side, or they experience jerky eye movements as they try to focus on a doctor’s finger when looking to either side.

All of the patients in the current study were seen after complaining of severe dizziness that had lasted for several hours continuously, and all had at least one risk factor for stroke. The researchers selected them to increase the chance that they would find strokes in this population. None of the patients had a history of previous dizzy spells and more than half sought care at the Peoria medical center’s ER, though some were inpatients at the hospital or were transferred from other area hospitals.

The researchers gave each patient an exam comprised of three eye-movement tests. They looked for inability to keep the eyes stable as patients heads were rotated rapidly to either side;, they looked for jerkiness as patients tracked a doctor’s finger to the right and left, and they checked eye position to see if one eye was higher than the other. Each patient then received an early MRI, the highest-quality neuroimaging test available to confirm stroke in dizzy patients. Patients with eye tests suggesting stroke but without stroke on the first MRI scan underwent a repeat scan.

In the end, 69 patients were diagnosed with stroke and 25 with inner-ear conditions. The remainder had other neurological problems. Using only the three eye-movement tests, the researchers had correctly diagnosed all of the strokes and 24 of 25 with inner-ear conditions. By contrast, initial MRI scans were falsely negative in 8 of the 69 stroke patients, who were later correctly diagnosed with follow-up MRIs.

Though the researchers emphasize the need to verify their results in a larger and more general population of patients with dizziness, they think the initial findings are “incredibly promising.” If they hold true, testing eye movements could have several advantages over MRI. For example, while the wait time for an MRI can be several hours or more, physicians can perform all three eye-movement tests in a minute or less. Also, the eye-movement tests are “basically free,” compared to $1000 or more for an MRI.

Free sounds good to me. And along with the simple tests that you can perform, we can save the lives of stroke victims. You do know what those tests are, don’t you? If you suspect someone is having a stroke, ask them to do three things. First have them SMILE! If the smile is noticeably crooked, it’s a warning sign. Then have them TALK. Ask them to repeat a simple sentence like “It’s sunny out today” or “I live on the beautiful island of Guam.” Then have them RAISE both arms and keep them in the air for five seconds. You can also grasp both their hands and tell them to squeeze with both of them.

If the person fails more than one of these simple tests, dial 911 immediately. With stroke, time=brain. The more time you wait, the more brain you lose. And if you’re anything like me, you don’t have a lot of brain to lose!

And now a lovely little positive tale for all us fish lovers!

KEEPING IT FRESH

An edible coating that extends the freshness of fish may also increase health benefits according to a new study done at Oregon State University.

The study, published in Food Chemistry, found fish oil added to an invisible “food wrap” made from citosan — a substance found in crustacean shells that keeps out bacteria and fungi — not only kept lingcod fillets fresh in the refrigerator for three weeks and in the freezer three months but also tripled the amount the omega-3 fatty acids normally found in lingcod.

The coating, which does not affect the color of the fish, also reduced rancidity both refrigerated and frozen samples when compared with the uncoated fillets and also kept the frozen fish moister. It delayed the growth of microorganisms in the fresh fillets, and it prevented their growth in the frozen ones.

The research indicates many health benefits including lowered heart disease risk linked to increased omega-3 fatty acids in the diet. While oily fish like salmon, mackerel and sardines are rich in omega-3 fatty acids, leaner fish such as cod, grouper and swordfish contain much less.

So, when are we going to see this fancy new coating at our local fish market? Not any time soon, I fear, but then fish never lasts very long around my house anyway because someone always eats it!

GLOBAL WARMING

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Well, after looking at the card files, I think it’s time to visit that eternal subject of conversation, the weather and of course, in today’s conversations, the weather also includes global warming. Today’s articles explain why global ‘warming’ might not be the problem!

One way to predict what the weather will be like in the future is to look at the past and find out what affected things way back then. One of the prime weather changers is volcanic ash and we’ll start with a couple of stories about what geologists have learned about past eruptions.

BOOM

Our first little tale involves the eruption of a ‘super-volcano’ in Indonesia. No, not Krakatoa, this happened much longer ago and the new research provides strong evidence that when the volcano Toba, located on the island of Sumatra, erupted about 73,000 years ago, it deforested much of central India, some 3,000 miles from the epicenter.

Toba put an estimated TWO HUNDRED CUBIC MILES of ash into the atmosphere, in the process creating a crater that’s 60 miles long and 20 miles wide (about the same size as Guam, but bigger). Ash from the event has been found in India, the Indian Ocean, the Bay of Bengal and the South China Sea.

The bright ash reflected sunlight away from the Earth, and all that dust covered the sky for at least six years, initiating an “Instant Ice Age” that — according to evidence in ice cores taken in Greenland — lasted about 1,800 years. During this instant ice age, world-wide temperatures dropped by as much 28 degrees.

The climactic effects of Toba have been a source of controversy for years, as is its impact on human populations. In 1998, research was published that proposed that the effects of the Toba eruption and the mini ice age that followed could explain the apparent bottleneck in human populations that geneticists believe occurred between 50,000 and 100,000 years ago. The lack of genetic diversity among humans alive today suggests that during this time period humans came very close to becoming extinct.

To address the limited evidence of the terrestrial effects of Toba, Stanley Ambrose and his colleagues pursued two lines of research: They analyzed pollen from a marine core taken in the Bay of Bengal that included a layer of ash from the Toba eruption, and they looked at carbon isotope ratios in fossil soil carbonates taken from directly above and below the Toba ash in three locations in central India.

Both lines of evidence revealed a distinct change in the type of vegetation in India immediately after the Toba eruption, the researchers report. The pollen analysis indicated a shift to more open conditions with fewer trees and fewer ferns. The change in vegetation and the loss of ferns, which grow best in humid conditions, suggests that things were significantly drier in central India for at least a thousand years after the Toba eruption.”

The dryness probably also indicates a drop in temperature, Ambrose said, “because when you turn down the temperature you also turn down the rainfall.”

Landsat satellite photo of Lake Toba, Sumatra, Indonesia. (Credit: Image courtesy of NASA / via Wikimedia Commons)

Now we’ll move forward in time to a much more recent eruption.

BOOM AGAIN

South Dakota State University researchers and their colleagues elsewhere in America and in France have found compelling evidence of a previously undocumented large volcanic eruption that occurred 200 years ago, in 1809. The discovery helps explain the record cold decade from 1810-1819.

Researchers made the finding by analyzing chemicals in ice samples from snow-capped Antarctica and Greenland in the Arctic. The year-by-year accumulation of snow in the polar ice sheets provides a marvelous permanent record (until global warming turns it into water) of what was in the atmosphere thousands of years in the past.

The researchers found large amounts of volcanic sulfuric acid in the snow layers of 1809 and 1810 in both Greenland and Antarctica. Climate records show that the entire decade of 1810-1819 which includes 1816 — the so-called “year without a summer” is probably the coldest for at least the past 500 years.

Scientists have long been aware of the massive eruption of Tambora, another Indonesian volcano, in 1815. That eruption, which killed more than 88,000 people in Indonesia, caused the worldwide cold weather in 1816 and after. But the cold temperatures in the early part of the decade, before that eruption, suggest Tambora alone could not have caused the climatic changes of the decade.

As we’ve already seen, volcanic eruptions chill the planet not only because of all the ash they blast into the atmosphere, but also because they release sulfur gases that form sulfuric acid aerosols that block sunlight. The new research shows that volcanic sulfuric acid came down at the opposite poles at precisely the same time. This means that the sulfur is from a single, large eruption of a volcano in 1809. Apparently, the Tambora eruption and the undocumented 1809 eruption were together responsible for the unusually cold decade.

The Tambora eruption was immense, sending about 100 million tons of sulfur gas into the atmosphere, but the ice core samples suggest the 1809 eruption was also very large — perhaps half the size of Tambora — and would also have cooled Earth for a few years. The researchers reason that, because the sulfuric acid is found in the ice from both polar regions, the eruption probably occurred in the tropics, as Tambora did, where wind patterns could carry volcanic material to the entire world, including both poles. Where did it erupt? No one knows yet, but one assumes we’ll eventually find out.

So exactly what does this mean for the rapidly warming Planet Earth? Read on.

AND YET ANOTHER

In the film The Day After Tomorrow, the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.

William Patterson, from the University of Saskatchewan in Canada, and his colleagues have shown that if you switch off water circulation in the North Atlantic, you can force the Northern hemisphere into a mini ‘ice age’ in a matter of months. Previous work has indicated that this process would take many years.

Around 12,800 years ago the Northern hemisphere was hit by a mini ice age, called the Younger Dryas. It has been nicknamed the ‘Big Freeze’, and it lasted about 1300 years. Geological evidence shows that the Big Freeze was caused by a sudden influx of freshwater, when the enormous glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans. This vast pulse of fresh water, which had a greater volume than the water contained in all of North America’s Great Lakes combined, diluted the North Atlantic conveyor belt (we learned it as the Gulf Stream) and brought it to a screeching halt. Without the warming influence of this ocean circulation, temperatures across the Northern hemisphere plummeted, ice sheets grew and human civilization fell apart.

Previous evidence from Greenland ice cores indicates that this sudden change in climate occurred over the space of a decade or so. The new data show that the change was amazingly abrupt, taking place over the course of a few months, or a year or two at most.

Patterson and his colleagues created the highest resolution record of the ‘Big Freeze’ event to date, from a mud core taken from an ancient lake, Lough Monreach, in Ireland. Researchers used a scalpel to slice layers from the core that were thinner than a sheet of paper. Each layer represented a time period of one to three months.

Carbon isotopes in each slice revealed how productive the lake was, while oxygen isotopes gave a picture of temperature and rainfall. At the start of the ‘Big Freeze’ the new record shows that temperatures plummeted and lake productivity stopped over the course of just a few years. Patterson said it would be like moving Ireland north of the Arctic Circle in a very short period of time.

Meanwhile, the isotope record from the end of the Big Freeze shows that it took around two centuries for the lake and climate to recover, rather than the abrupt decade or so recorded at the beginning. This makes sense because it would take time for the ocean and atmospheric circulation to turn on again.

Looking to the future Patterson says there is no reason why a ‘Big Freeze’ shouldn’t happen again. “If the Greenland ice sheet melted suddenly it would be catastrophic,” he says.

New research shows that switching off the Gulf Stream can force the Northern hemisphere into a mini ‘ice age’ in a matter of months. Previous work has indicated that this process would take years. (Credit: iStockphoto/Trevor Hunt)

And what’s going on with the Greenland ice sheet? Well, if it’s melting at the rapid rate shown by the southern ice cap and by the opening of the Northwest Passage, my guess is that we should be afraid, very afraid. Not of drowning, but freezing!