OREGON STATE UNIVERSITY

scientific research and advances

PNAS study: Ocean biota responds to global warming

CORVALLIS, Ore. – As the Earth warmed coming out of the last ice age, the rate of plankton production off the Pacific Northwest coast decreased, a new study has found, though the amount of organic material making its way to the deep ocean actually increased.

This suggests that during future climate warming, the ocean may be more efficient than previously thought at absorbing carbon dioxide from the atmosphere – at least in some regions – but raises new concerns about impacts on marine life.

Results of the study are being published online today in Proceedings of the National Academy of Sciences.

The ocean absorbs carbon dioxide like a sponge; scientists say that about one-third of all CO2   emitted historically by burning fossil fuels is now in the ocean. “This is a good news/bad news situation,” said Alan Mix, an Oregon State University oceanographer and co-author on the study. “It helps to slow the rise of CO2 in the atmosphere, but it makes the ocean more acidic.”

A major uncertainty has been how life in the ocean will respond to increasing CO2   and global warming. Growth of phytoplankton (microscopic plants such as diatoms) near the sea surface converts carbon dioxide into organic matter. When the plankton die, their organic remains either decompose in the surface ocean, or sink into the abyss.

This sinking of plankton effectively pumps CO2   out of the atmosphere. The so-called “biological pump” stores carbon in the deep sea, which is one way that biology influences global climate.

“It has been assumed that the amount of organic material that sinks to the sea floor would parallel that produced through photosynthesis near the sea surface,” said Mix, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Surprisingly, our study found that even as plant growth decreased, past warming actually enhanced the biological export of carbon to the deep sea, at least in the northeast Pacific.”

Lead author Cristina Lopes, a visiting scientist at Oregon State who is based at the Instituto Português do Mar e da Atmosfera (IPMA, Portuguese Sea and Atmosphere Institute) in Portugal, and colleague Michal Kucera at the Center for Marine Environmental Sciences at Germany’s University of Bremen, calculated the productivity of marine plankton during the last major global warming event leading to the end of the last ice age. They did so by examining fossil diatoms buried in sediment off the coast of Oregon.

A breakthrough came from applying neural network methods now used by financial and insurance industries. “Inspired by brain research, we adapted these machine learning methods to analyze the fossil record for a new view of how the ocean works,” Kucera said.

The researchers found that during the ice age, the carbon trapped in plankton off Oregon was mostly recycled rather than exported to the deep ocean. As the ice age waned and the ocean warmed, plant growth decreased while carbon export increased.

“This counterintuitive effect was driven by a shift in ecosystems to one dominated by large diatoms,” Lopes said. “Those diatoms bloomed, then sank fast when they died.”

The researchers say their findings don’t necessarily mean that the ocean can continue to absorb increasing amounts of CO2   indefinitely, but that computer models of the ocean’s carbon cycle will need to take into account that plant productivity and carbon export are not always linked.

Evidence that export of carbon to the deep sea increases in some regions during long-term warming may help to slow down global climate change, but it may make some other impacts worse, the researchers point out. For example, as the extra sinking organic matter decomposes, it consumes oxygen dissolved in seawater – and loss of oxygen in the ocean is a growing concern.

Low-oxygen “dead zones” have appeared off the coast of Oregon several times in recent years.

“If these connections between warming and enhanced carbon export that we’ve found in past climate changes are triggered in the future, we can expect those marine dead zones to show up more frequently,” Mix said.

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Alan Mix, 541-737-5212, amix@coas.oregonstate.edu

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Arachnodiscus

Lionfish analysis reveals most vulnerable prey as invasion continues

CORVALLIS, Ore. – If you live in lionfish territory in the Atlantic Ocean, the last thing you want to be is a small fish with a long, skinny body, resting by yourself at night, near the bottom of the seafloor.

If so, your chances of being gobbled up by a lionfish increase by about 200 times.

Findings of a study on lionfish predation behavior, which may also apply to some other fish and animal species, have shed some new light on which types of fish are most likely to face attack by this invasive predator, which has disrupted ecosystems in much of the Caribbean Sea and parts of the Atlantic Ocean.

The research has been published in the Journal of Animal Ecology by scientists from Oregon State University and Simon Fraser University. It used the study of lionfish to gain broader insights into how predators select their prey, and developed a new method for predicting diet selection across various prey assemblages.

“With species now moving all over the world in both marine and terrestrial systems, we need to know who will eat whom when species encounter each other for the first time,” said Stephanie Green, the David H. Smith Conservation Research Fellow in the OSU College of Science, who has done extensive studies of lionfish.

“Normally, predator-prey experiments take a lot of effort and time,” Green said. “But there are mathematical techniques that can help us better understand what is happening when we observe animals hunting in the wild, and why some species get eaten and others don’t.”

Green said that researchers want to identify common features across the animal kingdom that make some species more vulnerable than others.

“We’re playing catch-up on this,” she said. “However, with the case of species invasions, a much better understanding of which native species are at risk can help us target management intervention. This could help avoid extirpations and, in the worst-case scenario, more outright extinctions.”

This study is one of the first to identify general traits of prey that predict vulnerability to predation, and examine diet selection at different spatial scales. Some of the findings may be relevant to other invasive species problems, such as expansion of the Burmese python in the Florida Everglades and the spread of Asian tiger prawn into the Gulf of Mexico.

The study also showed that although lionfish have a voracious appetite and will eat almost any fish smaller than they are, they do have their favorites.

They find it easier to stalk and attack solitary fish, rather than those in schools. They like to hunt at dusk, near the bottom, and for some reason tend to avoid fish that clean off parasites from other fish species that are common in a marine environment.

“Fish that clean parasites off of other fish appear to be avoided by lionfish,” Green said. “Those that don’t will be much harder hit.”

Having all the traits that make them vulnerable, for instance, raises a serious question about the ability of some species to survive the lionfish invasion, such as the Exuma Goby, a small fish native to one area of The Bahamas. It has many traits lionfish prefer.

OSU researchers are working with the International Union for Conservation of Nature to help identify some of the species and problem areas most at risk of extinction from the lionfish invasion, and where control of the invaders should be prioritized.

Lionfish are now established on coral reefs across the western Atlantic Ocean, Caribbean Sea and Gulf of Mexico, and the invasion continues to spread while reef biodiversity and biomass rapidly declines. The high rate of fish mortality also poses an additional threat to coral reefs themselves, which can become covered with algae if enough fish are not present to eat the algae and keep it under control.

The research was supported by the Natural Science and Engineering Research Council of Canada and the David H. Smith Conservation Research Program.

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Stephanie Green, 778-808-0758

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Reef research
Stephanie Green


Hunting lionfish
Hunting lionfish


Lionfish
Hunting at dusk


Algae on coral reef
Algae-covered corals


“Picky Eaters,” a Podcast about species diet preferences, is online at: http://bit.ly/1vpMcAA

Biomarker could provide early warning of kidney disease in cats

CORVALLIS, Ore. – Researchers from Oregon State University and other institutions have developed a new biomarker called “SDMA” that can provide earlier identification of chronic kidney disease in cats, which is one of the leading causes of their death.

A new test based on this biomarker, when commercialized, should help pet owners and their veterinarians watch for this problem through periodic checkups, and treat it with diet or other therapies to help add months or years to their pet’s life.

Special diets have been shown to slow the progression of this disease once it’s identified.

The findings were made in a controlled study of 32 healthy, but older cats, and have been published in The Veterinary Journal by researchers from OSU and IDEXX Laboratories. They demonstrated the efficacy of a biomarker that could form the basis for a new diagnostic test.

“Chronic kidney disease is common in geriatric cats and often causes their death,” said Jean Hall, a small animal medical expert and professor in the OSU College of Veterinary Medicine. “Damage from it is irreversible, but this is an important advance, in that we should be able to identify the problem earlier and use special diets to slow the disease.”

Many of these same health issues also relate to older dogs, and in continued research scientists believe they may make similar findings.

Renal decline is normal in most cats, experts say, as they reach 12-18 years of age, and along with issues such as cancer and gastrointestinal disease is one of the more common causes of death. But studies have shown that the problem can also be managed with special foods that reduce protein and phosphorus, while adding fish oil, antioxidants, L-carnitine and medium-chain triglycerides.

This biomarker was able to identify the onset of kidney disease in cats on average 17 months earlier than any existing approach, and in at least one case four years earlier. With special diets and care, some cats have lived several years after the disease was diagnosed.

The only existing test for the disease, which has been used for decades, is a blood test that checks creatinine levels, a marker of the breakdown of muscle protein. However, cats lose lean body mass as they age, so creatinine levels may be normal.  SDMA is not influenced by lean body mass and thus more accurately diagnoses the loss of kidney function, even if lean body mass has decreased.

The early symptoms of this disease are fairly non-specific, such as loss of appetite, weight loss, or vomiting.

The cats in this research were housed at the Science and Technology Center of Hill’s Pet Nutrition Inc.  The company provided data and samples for analysis in order to better understand the dietary needs of cats with early renal disease, and initiated the study to investigate how best to lengthen and enrich the lives of cats with the condition.

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Jean Hall, 541-737-6537

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Aging cat
Aging cat

New technology may speed up, build awareness of landslide risks

CORVALLIS, Ore. – Engineers have created a new way to use lidar technology to identify and classify landslides on a landscape scale, which may revolutionize the understanding of landslides in the U.S. and reveal them to be far more common and hazardous than often understood.

The new, non-subjective technology, created by researchers at Oregon State University and George Mason University, can analyze and classify the landslide risk in an area of 50 or more square miles in about 30 minutes - a task that previously might have taken an expert several weeks to months. It can also identify risks common to a broad area rather than just an individual site.

And with such speed and precision, it reveals that some landslide-prone areas of the Pacific Northwest are literally covered by landslides from one time or another in history. The system is based on new ways to use light detecting and ranging, or lidar technology, that can seemingly strip away vegetation and other obstructions to show land features in their bare form.

“With lidar we can see areas that are 50-80 percent covered by landslide deposits,” said Michael Olsen, an expert in geomatics and the Eric HI and Janice Hoffman Faculty Scholar in the OSU College of Engineering. “It may turn out that there are 10-100 times more landslides in some places than we knew of before.

“We’ve always known landslides were a problem in the Pacific Northwest,” Olsen said. “Many people are just now beginning to realize how big the problem is.”

An outline of the new technology was recently published in Computers and Geosciences, a professional journal.

Oregon and Washington, especially in the Coast Range and Cascade Range, are already areas commonly known to have landslides, and as a result Oregon’s Department of Geology and Mineral Industries has become a national leader in mapping of them, Olsen said. But previous approaches are slow, and the new technology, called a Contour Connection Method, could radically speed up widespread mapping, and build both professional and public awareness of the issue.

Despite the prevalence and frequency of landslides, they are not generally covered by most homeowner insurance policies; coverage can be purchased separately, but most people don’t. And with increasing population growth, more and more people are moving into more remote locations, or building in scenic areas near the hills around cities where landslide risk might be high.

“A lot of people don’t think in geologic terms, so if they see a hill that’s been there for a long time, they assume there’s no risk,” said Ben Leshchinsky, a geotechnical engineer in the OSU College of Forestry. “And many times they don’t want to pay extra to have an expert assess landslide risks or do something that might interfere with their land development plans.”

Lidar is already a powerful tool, but the new system developed at OSU offers an automated way to improve the use of it, and could usher in a new era of landslide awareness, experts say. Information could be more routinely factored into road, bridge, land use, zoning, building and other decisions.

With this technology, a computer automatically looks for land features, such as suddenly steeper areas of soil, that might be evidence of a past landslide. It then searches the terrain for other features, such as a “toe” of soils at the base of the landslide. And in minutes it can make unbiased, science-based classifications of past landslides that consistently use the same criteria.

The technology was applied to the region surrounding the landslide of March, 2014, that killed 43 people near the small town of Oso, Washington. In about nine minutes it was able to analyze more than 2,200 acres and many prehistoric landslide features that are readily apparent in lidar images, in this region known for slope instability.

Eventually, adaptations of the technology might even allow for real-time monitoring of soil movement, the researchers said.

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Michael Olsen, 541-737-9327

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Landslide detection

Landslide detection




Landslide map of region
Mapped landslide inventory




Oso landslide
Oso, Washington landslide

Virulent bacteria affecting oysters found to be a case of mistaken identity

CORVALLIS, Ore. -  The bacteria that helped cause the near-ruin of two large oyster hatcheries in the Pacific Northwest have been mistakenly identified for years, researchers say in a recent report.

In addition, the study shows that the bacteria now believed to have participated in that problem are even more widespread and deadly than the previous suspect.

Although the hatchery industry has largely recovered, primarily by better control of ocean water acidity that was also part of the problem, the bacterial pathogens remain a significant concern for wild oysters along the coast, researchers said.

For many years, it had been believed that the primary bacteria causing oyster larval death in the Pacific Northwest was Vibrio tubiashii. Now, scientists say that most, or possibly all of the bacterial problem was caused by a different pathogen, Vibrio coralliilyticus, a close cousin that’s now known to be even more virulent to Pacific oysters.

The findings were published in Applied and Environmental Microbiology, by researchers from the College of Veterinary Medicine at Oregon State University, the U.S. Department of Agriculture, and Rutgers University. The research was supported by the USDA.

“These bacteria are very similar, they’re close cousins,” said Claudia Häse, an OSU associate professor and expert in microbial pathogenesis. “V. coralliilyticus was believed to primarily infect warm water corals and contributes to coral bleaching around the world. It shares some gene sequences with V. tubiashii, but when we finally were able to compare the entire genomes, it became apparent that most of what we’re dealing with in the Pacific Northwest is V. coralliilyticus.”

Scientists now say that V. coralliilyticus is not only far more widespread than previously believed, but that it can infect a variety of fish, shellfish and oysters, including rainbow trout and larval brine shrimp. And it appears to be the primary offender in bacterial attacks on Pacific Northwest oyster larvae.

OSU experts have developed a rapid diagnostic assay for this bacteria that is nearing commercialization, and it may help assess problems both in oyster and coral health, Häse said.

“Although we’ve largely addressed the problems the hatcheries face, these bacteria continue to pose threats to wild oysters,” Häse said. “And corals are still declining in many places, the Great Barrier Reef in Australia is dying at an alarming rate. Better diagnostics might help in all of these situations.”

In what’s now understood to be a problem with multiple causes, these pathogenic bacteria were involved in major crashes of oyster hatcheries, causing shortages in seed oysters for commercial producers. Dramatic losses were suffered in a Netarts Bay, Oregon, hatchery in 2005, and Washington hatcheries were also hard hit. Bacterial infection, water acidity, oxygen depletion and rising seawater temperatures are all believed to have been part of the problem.

By better monitoring and control of water acidity, which was one serious concern, hatcheries have been able to regain most of their productive capabilities. Wild oysters, however, continue to face the multiple pressures from rising acidity, pathogenic bacteria and other forces that have led to serious hatchery mortality.

Those problems have not been made any easier by the lack of funding for identification and studies of the bacteria that researchers now know to be causing infection.

In laboratory tests, strains of V. tubiashii did not show significant pathogenicity to Pacific oysters. V. coralliilyticus, by contrast, is highly infectious to both Pacific and Eastern oyster larvae, and perhaps other shellfish species.

“The Vibrio genus and many bacteria associated with it are a huge problem in fish and shellfish aquaculture, and we should be studying them more aggressively,” Häse said. “V. coralliilyticus, in particular, has a very powerful toxin delivery system, and vibrios are some of the smartest of all bacteria. They can smell, sense things and swim toward a host.”

It’s believed that increasing environmental stresses may make oysters and other marine life more vulnerable to these types of bacterial infection, researchers say.

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Claudia Häse, 541-737-7001

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Oyster larvae
Oyster larvae

New advance in cryopreservation could change management of world blood supplies

CORVALLIS, Ore. – Engineers at Oregon State University have identified a method to rapidly prepare frozen red blood cells for transfusions, which may offer an important new way to manage the world’s blood supply.

It’s already possible to cryopreserve human red blood cells in the presence of 40 percent glycerol, but is rarely done because of the time-consuming process to thaw and remove the glycerol from the blood. This can take an hour or more and makes it logistically difficult to use frozen blood.

However, some initial experiments and computer modeling of a proposed new process suggest that this hour-long process can be reduced to as little as three minutes, using a membrane-based, microfluidic device. This could make it far more feasible to use frozen blood in emergency or time-constrained medical situations.

The findings were just reported in the journal Biomicrofluidics.

“Only a small fraction of our blood supply is now frozen, because it’s often impractical to wait so long when a transfusion is needed immediately,” said Adam Higgins, an expert in medical bioprocessing and associate professor in the OSU School of Chemical, Biological and Environmental Engineering.

“Because of that, our entire system depends on constantly balancing the use and supply of blood products that can only last six weeks or less with refrigeration,” he said. “This is difficult, and can lead to loss of outdated blood, periodic shortages, and other inefficiencies that could be solved with the use of frozen blood.”

Researchers in the OSU College of Engineering, however, have become national leaders in the science of microfluidics, which uses microchannel-based approaches to processing fluids for various purposes, ranging from more efficient heat pumps to innovative methods for kidney dialysis.

In the case of frozen blood, extremely tiny microchannel plates and membranes could be used to precisely control removal of glycerol from blood at a time scale of seconds. This would allow much more rapid thawing of frozen blood, which isn’t possible using the centrifugal cell washers that have been around for decades and are the only other way to remove glycerol from the blood.

The new approach should work, OSU experts say.

“Our results pave the way for development of a clinical device for ultra-rapid glycerol extraction, which would greatly improve the logistics of blood banking,” the researchers wrote in their report.

According to their report, each year more than 100 million blood donations are collected worldwide, enabling millions of life-saving transfusions. But refrigerated blood has a short shelf life, and some recent studies even suggest that “older” blood being used within what’s believed to be an acceptable refrigeration period may be linked to severe complications.

Cryopreservation could extend the shelf life of blood from weeks to years; dramatically smooth out the undependable supplies of blood; and according to recent research, produce cryopreserved red blood cells that have superior biochemical and tissue oxygenation capabilities compared to refrigerated red blood cells.

This research has been supported by a CAREER Award from the National Science Foundation.

In continued studies, researchers said they hope to create working prototypes of the needed technology for further development and testing of the concept. An optimized process may also be even faster than the three minutes now being predicted, they said.

Media Contact: 
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Adam Higgins, 541-737-4600

“Eyespots” in butterflies shown to distract predatory attack

CORVALLIS, Ore. – Research has demonstrated with some of the first experimental evidence that coloration or patterns can be used to “deflect” attacks from predators, protecting an animal’s most vulnerable parts from the predators most likely to attack them.

The study, published today in Proceedings of the Royal Society B, in fact shows that one species of butterfly uses its “eyespots” not only for protection, but varies the color and intensity of them by season as the types of predators change.

The findings were made by researchers from Oregon State University, Yale University and four other institutions.

“Eyespots are conspicuous, they draw your attention and are thought to be used by many animal species to avoid death or attack, by either startling or confusing the predator,” said Katy Prudic, lead author on the study and a researcher with the Department of Integrative Biology in the College of Science at Oregon State University. “Many insects have eyespots, which suggests they are an important adaptation.”

The butterfly species studied, Bycyclus anyana, produces about five generations a year during both wet and dry seasons in its native habitat. Through a process scientists call “phenotypic plasticity,” the same genes can produce two different eyespot patterns in the adults. Warm temperatures of the wet season create large and bright eyespots, while cool temperatures common in the dry season produce dull and small eyespots.

During the wet season, the large eyespots make a colorful target for attack, conceptually similar to a matador waving a cape that distracts a charging bull into attacking the wrong thing.

In this season, predatory insects such as the praying mantids are their greatest enemy, and the showy eyespots on the wings led the mantids to attack the butterfly wings rather than the more vulnerable body or head. The wings are badly damaged, but the insect can escape and live to reproduce.

During the dry season, most insect predators are dead but birds abound. For birds, the smaller, dull eyespots make the butterfly more difficult to detect and consume.

“Having the right type of eyespot in the right season allowed the butterflies to live long enough to lay eggs and have more offspring in the next generation,” Prudic said. “With the wrong eyespot at the wrong time, they were quickly annihilated by the mantids.”

Color pattern has always been a form of protection against predators in nature, Prudic said. It can take the form of camouflage, mimicry, delaying or redirecting attacks. But studies that observed and hypothesized about such changes have been difficult to document in controlled experiments such as this.

Eyespots are one of nature’s favorite forms of misdirection, shared by fish, frogs, birds, and many insects. Aside from deflecting attack, they can also be used as a “startle” mechanism, being flashed just long enough to delay attack briefly and allow a species to escape. Researchers also believe eyespots can play a role in sexual attraction and mate selection.

This research was supported by the Yale Institute for Biospheric Studies, the Donnelley family and the Singapore Ministry of Education.

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Kathleen Prudic, 541-737-5736

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Wet season
Wet season


Dry season
Dry season


Butterfly eyespots YouTube video http://youtu.be/0d9fzaxjvYs


Mantids attack YouTube video http://youtu.be/BObK3vzXf7g

“Antibiogram” use in nursing facilities could help improve antibiotic use, effectiveness

PORTLAND, Ore. – Use of “antibiograms” in skilled nursing facilities could improve antibiotic effectiveness and help address problems with antibiotic resistance that are becoming a national crisis, researchers conclude in a new study.

Antibiograms are tools that aid health care practitioners in prescribing antibiotics in local populations, such as a hospital, nursing home or the community. They are based on information from microbiology laboratory tests and provide information on how likely a certain antibiotic is to effectively treat a particular infection.

The recent research, published by researchers from Oregon State University in Infection Control and Hospital Epidemiology, pointed out that 85 percent of antibiotic prescriptions in the skilled nursing facility residents who were studied were made “empirically,” or without culture data to help determine what drug, if any, would be effective.

Of those prescriptions, 65 percent were found to be inappropriate, in that they were unlikely to effectively treat the target infection.

By contrast, use of antibiograms in one facility improved appropriate prescribing by 40 percent, although due to small sample sizes the improvement was not statistically significant.

“When we’re only prescribing an appropriate antibiotic 35 percent of the time, that’s clearly a problem,” said Jon Furuno, lead author on the study and an associate professor in the Oregon State University/Oregon Health & Science University College of Pharmacy.

“Wider use of antibiograms won’t solve this problem, but in combination with other approaches, such as better dose and therapy monitoring, and limiting use of certain drugs, we should be able to be more effective,” Furuno said.

“And it’s essential we do more to address the issues of antibiotic resistance,” he said. “We’re not keeping up with this problem. Pretty soon, there won’t be anything left in the medical cabinet that works for certain infections.”

In September, President Obama called antibiotic resistant infections “a serious threat to public health and the economy,” and outlined a new national initiative to address the issue. The Centers for Disease Control and Prevention has concluded that the problem is associated with an additional 23,000 deaths and 2 million illnesses each year in the U.S., as well as up to $55 billion in direct health care costs and lost productivity.

Antibiograms may literally be pocket-sized documents that outline which antibiotics in a local setting are most likely to be effective. They are often used in hospitals but less so in other health care settings, researchers say. There are opportunities to increase their use in nursing homes but also in large medical clinics and other local health care facilities for outpatient treatment. The recent study was based on analysis of 839 resident and patient records from skilled nursing and acute care facilities.

“Antibiograms help support appropriate and prudent antibiotic use,” said Jessina McGregor, also an associate  professor in the OSU/OHSU College of Pharmacy, and lead author on another recent publication on evaluating antimicrobial programs.

“Improved antimicrobial prescriptions can help save lives, but they also benefit more than just an individual patient,” McGregor said. “The judicious use of antibiotics helps everyone in a community by slowing the spread of drug-resistant genes. It’s an issue that each person should be aware of and consider.”

Multi-drug resistant organisms, such as methicillin-resistant Staphylococcus aureus, or MRSA, and other bacterial attacks that are being called “superinfections” have become a major issue.

Improved antibiotic treatment using a range of tactics, researchers say, could ultimately reduce morbidity, save money and lives, and improve patients’ quality of life.

The research led by Furuno was supported by the U.S. Department of Health and Human Services. Collaborators include researchers from the University of Maryland School of Medicine, Denver Health and Hospital Authority, University of Colorado Health Sciences Center, and Agency for Healthcare Research and Quality in Maryland.

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Jon Furuno, 503-418-9361

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Antibiotic resistant bacteria
MRSA bacteria

PNAS Commentary: Study sheds new light on sea level rise at last ice age

CORVALLIS, Ore. – A new study published last week in Proceedings of the National Academy of Sciences calculated global sea level changes over the past 35,000 years, concluding that in order to account for the amount of sea level lowering at the peak of the last ice age, much more ice would have had to have been tied up on land than previously thought.

The researchers further concluded that most of this “excess ice” – or an amount greater than today – was likely added to the present Antarctic ice sheets. Lead researcher Kurt Lambeck from Australian National University and colleagues estimated that during the last glacial maximum, these ice sheets had enough excess ice to increase global sea levels some 25 meters, much more than the 10-meter excess scientists previously estimated.

These new findings are critical to understanding the sources of sea level rise that is taking place today in response to a warming climate, according to Peter Clark, an Oregon State University paleoclimatologist, who co-authored a commentary piece on the research in the latest edition of PNAS, which will be published this week.

“Essentially, this new study implies that the Antarctic ice sheets are losing less mass today than had previously been estimated through satellite measurements,” said Clark, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “During the last ice age, the ice sheets were so large and heavy they pushed the entire land mass down and displaced the viscous mantle below.

“As the ice sheets began to retreat, the land mass beneath began to rise due to the area below being refilled by the mantle as it slowly flows back,” Clark added. “This process is continuing today and needs to be accounted for when estimating from satellites current mass loss from the Antarctic ice sheets. If the effect of this process is bigger than previously thought, then current mass loss is less than we thought.

“If this is the case, then at least some of the rising sea level today that is being attributed to loss of the Antarctic ice sheets must have some other source.”

The other main sources of sea level rise today are from the loss of the Greenland ice sheets, receding glaciers on a global basis, and the expansion of the ocean itself through warming.

Studies show that sea level today is rising globally at a rate of about 3.0 millimeters a year, and about 1/10th of that (0.3 mm) was thought to be from Antarctica.

“If this new study holds up, that means that the rate of contribution from Antarctica to today’s rise is less than 0.3 millimeters,” Clark said. “Learning the source of the increase will help us better understand how sea level rise may play out in the future.”

Prior to Lambeck’s study, the prevailing theory among many scientists was that Antarctic ice sheets contained enough ice to raise global sea levels about 70 meters if it had melted all at once some 21,000 years ago. These ice sheets today hold enough water to raise sea levels 60 meters – about 10 meters less than during the last glacial maximum.

But the study by Lambeck and colleagues, which was based on a comprehensive analysis of nearly 1,000 paleo-sea level markers, suggests instead that the Antarctic had enough mass during the last ice age to raise global sea levels some 85 meters if melted.

In contrast, the entire Greenland ice sheet today contains enough ice to raise global sea levels about seven meters, if melted at once.

Clark, who was a coordinating lead author on sea level rise for the 2013 Intergovernmental Panel on Climate Change (IPCC) report, cautioned that there may be other explanations for the “excess ice” thought to account for the lower sea levels during the last ice age. These might include a greater influence from the lateral viscosity of the Earth’s mantle fluid, the possibility of a large, grounded East Siberian ice sheet, and the influence of physical factors on organisms used as proxies to determine sea level rises.

Lev Tarasov of Memorial University of Newfoundland, co-authored the commentary with Clark.

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Peter Clark, 541-737-1247; clarkp@geo.oregonstate.edu

“Mild” control of systolic blood pressure in older adults is adequate: 150 is good enough

CORVALLIS, Ore. – A broad review of the use of medications to reduce blood pressure has confirmed that “mild” control of systolic pressure is adequate for adults age 65 or older - in the elderly, there’s no clear benefit to more aggressive use of medications to achieve a lower pressure.

Historically, most medical practitioners tried to achieve control of systolic pressure – the higher of the two blood pressure readings – to 140 or less. Recently changed guidelines now suggest that for adults over 60, keeping the systolic pressure at 150 or less is adequate, and this extensive analysis confirms that.

However, researchers also say in the report that more work needs to be done studying blood pressure in older populations, since most of the research, and the medical guidelines based on them, were done using predominately younger adults.

The review was just published in Drugs & Aging, a professional journal, by scientists from the College of Pharmacy at Oregon State University and Oregon Health & Science University.

“The goal of a systolic pressure at or below 140 has been around a long time, and there’s still skepticism among some practitioners about accepting a higher blood pressure,” said Leah Goeres, an OSU postdoctoral fellow and lead author on the publication.

“Keeping systolic blood pressure in older adults below 150 is important, it’s what we consider a mild level of control,” Goeres said. “But for older people that level is also good enough. After an extensive review, there was no significant evidence that more intensive management is necessary.”

The issue about how low is low enough, researchers say, is important because blood pressure medications can have unwanted side effects that increase as higher dosages of medications are used. The problem is common – in the United States, about 70 percent of adults age 65 or older have hypertension, and millions of people take medication to control it.

One of the more significant side effects is what’s called “orthostatic hypotension,” a condition in which a person’s blood pressure can suddenly fall when they rise or stand, making them feel light-headed or dizzy, and sometimes leading to dangerous falls. More than 30 percent of people over the age of 80 have this problem.

High blood pressure is a serious health concern, but also one of the most treatable with medication, if such things as diet, exercise, weight management or lifestyle change prove inadequate.  Hypertension is often called the “silent killer” because it causes few obvious symptoms, but it weakens blood vessels and has been linked to higher levels of heart attacks, kidney disease and especially stroke.

“There’s clearly a value to controlling blood pressure, enough to keep it at 150 or less,” said David Lee, an OSU assistant professor of pharmacy practice. “Keeping blood pressure within acceptable levels will lower death rates. But as people get older, there’s less clear evidence that stringent control of systolic blood pressure is as important.”

The researchers said a goal for the future should be to do more studies specifically with older adult populations and try to identify health situations and conditions that might benefit from different types of management. Such “individualized” treatments, they said, would consider a person’s entire health situation instead of treating them based on findings made with large groups.

In this study, the researchers did not find that one approach or another to lowering blood pressure stood out and was clearly better than other alternatives. A variety of medications can be used to treat the condition.

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