“Study: Preventive mastectomy doesn't benefit most (seattlepi.com)” plus 3 more

Study: Preventive mastectomy doesn't benefit most (seattlepi.com)
Antifreeze proteins can stop ice melt, new study finds (Science Daily)
Antifreeze proteins can stop ice melt, new study finds (EurekAlert!)
El Nino and a pathogen killed Costa Rican toad, study finds (PhysOrg)

Study: Preventive mastectomy doesn't benefit most (seattlepi.com)

Posted: 01 Mar 2010 05:52 PM PST

Breast cancer patients are increasingly having preventive surgery to remove the unaffected breast, but a new study suggests it's not beneficial for the vast majority of women who undergo it.

Researchers at the University of Texas M.D. Anderson Cancer Center on Thursday reported that an analysis of the records of more than 100,000 patients revealed a survival benefit in 6 percent of those who opted to have a double mastectomy. Most who benefited fit a particular profile that doctors can easily identify at diagnosis.

"It's important for women to understand that, except for one subset of breast cancer patients, they don't need to do this," said Dr. Isabelle Bedrosian, an M.D. Anderson professor of surgical oncology and one of the study's two lead authors. "Hopefully, it'll reassure patients wondering if they should."

The observational study, which was published online Thursday in the Journal of the National Cancer Institute, found a double mastectomy offers a slight but real benefit to patients 50 and younger whose cancer is estrogen receptor negative and in the early stages. The study is the first to find such an association between the procedure and survival.

The study found no benefit among patients 60 or older undergoing a double mastectomy and murky results among those aged 50 to 60.

Women diagnosed with breast cancer are known to have an increased risk of developing breast cancer in the opposite breast. But the study found that preventive surgery on the opposite breast had little survival benefit, save for the one subset, either because patients die from the cancer they already have or from other medical conditions, or because the risk isn't realized in their lifetime.

Surgeries increasing

The number of double mastectomies has grown dramatically in recent years. Many patients who choose that option say they do so because it gives them peace of mind.

Previous studies have found that the number more than doubled from 1998 to 2003, and Bedrosian said based on her experience the trend has seemingly continued to escalate. Statistics from 2003 show 11 percent of women having a mastectomy opted for one in their disease-free breast as well.

The increase is attributed to scans that can detect smaller, earlier cancers; genetic tests that can warn women of the inherited risk they face; and better plastic surgery techniques that make reconstructive surgery more appealing than it once was.

Bedrosian's team identified 107,106 women in the National Cancer Institute's Surveillance, Epidemiology and End Results registry who had a mastectomy to treat Stage I to Stage III breast cancer. Among that group, 8,902 women also had their unaffected breast removed.

At a five-year follow-up, 88.5 percent of those who had the elective mastectomy were alive, compared to 83.7 of those who didn't.

After controlling for different variables, the M.D. Anderson team found that the younger women with early-stage tumors not fueled by estrogen had a survival benefit of 4.8 percent at five years, meaning for every 100 patients, fewer than five who would have died without the additional surgery were still alive. The prognosis is usually poorer for estrogen receptor-negative patients.

No other group showed a clear benefit.

One expert's response to the data was to recommend that any woman requesting an elective mastectomy wait a year before having it done.

"In a younger woman with (estrogen receptor)-negative disease, an (elective) mastectomy may be considered," said Dr. Victor Vogel, national vice president for research at the American Cancer Society. "In the vast majority of women older than 50 with ER-positive disease, prudent waiting is probably the most appropriate."

Information for patients

One of Bedrosian's patients was happy to have the data. Diagnosed in December with Stage II estrogen receptor-negative breast cancer, the 33-year-old woman hadn't thought of a double mastectomy until learning of her particular susceptibility to the disease spreading.

"For me, it was a very matter-of-fact decision," said Rachel Jackson, an Austin triathlete who has yet to schedule either mastectomy. "I'm planning to live to 70 or 80."

Nearly 200,000 U.S. women are diagnosed with breast cancer every year, and 40,000 die of it. The majority do not have mastectomies.

Bedrosian emphasized that the study findings should not be interpreted as "a uniform mandate."

"This is still a decision to be made by the patient after talking with her doctor," Bedrosian said. "A younger woman with early-stage ER-negative breast cancer might have good reason not to want a (double) mastectomy, and an older woman -- say, with a significant family history -- might have good reason to want one."

Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

Antifreeze proteins can stop ice melt, new study finds (Science Daily)

Posted: 01 Mar 2010 01:29 PM PST

ScienceDaily (Mar. 2, 2010) — The same antifreeze proteins that keep organisms from freezing in cold environments also can prevent ice from melting at warmer temperatures, according to a new Ohio University and Queen's University study published today in the Early Edition of the journal Proceedings of the National Academy of Sciences.

Antifreeze proteins are found in insects, fish, bacteria and other organisms that need to survive in cold temperatures. These proteins protect the organisms by arresting the growth of ice crystals in their bodies. The new study not only has implications for understanding this process in nature, but also for understanding the superheating of crystals in technologies that use superconductor materials and nanoparticles.

Twenty years ago, researchers proposed that antifreeze proteins can create superheating by suppressing melting at temperatures higher than the equilibrium melting point.

"During recrystallization, a larger ice crystal grows while a smaller one melts. Antifreeze proteins can help control both of these processes," explained Ido Braslavsky, an associate professor of physics and astronomy at Ohio University who worked on the study with lead author Yeliz Celik, a doctoral student in physics at Ohio University, and Professor Peter Davies of Queen's University in Canada.

The team's study, supported by the National Science Foundation and the Canadian Institutes for Health Research, presents the first direct measurements of the superheating of ice crystals in antifreeze protein solutions, Celik said.

In addition, the researchers provide the first experimental evidence that superheated ice crystals can be stabilized above the melting point for hours, at a maximum temperature of about .5 degree Celsius. Superheated crystals rarely stay stable for long periods of time, and previous studies showed that stabilization only occurs under unique conditions, Braslavsky explained.

The researchers used two techniques in the study, fluorescence microscopy and sensitive temperature control of a solution within a thin cell. In order to track the position of the antifreeze protein on an ice crystal, the researchers attached a second protein to the antifreeze protein -- the green fluorescent protein, which glows under certain conditions. The scientists then placed the antifreeze protein solution in the thin cell, which allowed them to observe the fluorescence signal from the protein while finely controlling the ice crystal's temperature.

Although the study reveals that these proteins can suppress ice melting up to a certain point, the protein's ability to suppress ice growth is much stronger. The hyperactive antifreeze proteins used in the study were more capable of suppressing melting than the moderately active ones, Braslavsky said.

These findings potentially could make the process of ice recrystallization inhibition more efficient for applications such as maintaining the quality of frozen foods, Braslavsky said.

"Antifreeze proteins that inhibit growth and melt are essential for protection against freeze and thaw damages," he said. "Big crystals (that occur in the recrystalization process) separate cell walls and damage the integrity of the tissue."

In additional to Celik, Braslavsky and Davies, co-authors of the study include Maya Bar of the Weizmann Institute of Science and Laurie Graham and Yee-Foong Mok of Queen's University.

Story Source:

Adapted from materials provided by Ohio University, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.

Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

Antifreeze proteins can stop ice melt, new study finds (EurekAlert!)

Posted: 01 Mar 2010 12:21 PM PST

Public release date: 1-Mar-2010
[ | E-mail |

Share ]

Contact: Andrea Gibson
gibsona@ohio.edu
740-597-2166
Ohio University

Scientists publish first direct measurements of 'superheating' phenomenon

ATHENS, Ohio (March 1, 2010) The same antifreeze proteins that keep organisms from freezing in cold environments also can prevent ice from melting at warmer temperatures, according to a new Ohio University and Queen's University study published today in the Early Edition of the journal Proceedings of the National Academy of Sciences.

Twenty years ago, researchers proposed that antifreeze proteins can create superheating by suppressing melting at temperatures higher than the equilibrium melting point.

The researchers used two techniques in the study, fluorescence microscopy and sensitive temperature control of a solution within a thin cell. In order to track the position of the antifreeze protein on an ice crystal, the researchers attached a second protein to the antifreeze proteinthe green fluorescent protein, which glows under certain conditions. The scientists then placed the antifreeze protein solution in the thin cell, which allowed them to observe the fluorescence signal from the protein while finely controlling the ice crystal's temperature.

These findings potentially could make the process of ice recrystallization inhibition more efficient for applications such as maintaining the quality of frozen foods, Braslavsky said.

In additional to Celik, Braslavsky and Davies, co-authors of the study include Maya Bar of the Weizmann Institute of Science and Laurie Graham and Yee-Foong Mok of Queen's University.

Contacts: Ido Braslavsky, (740) 597-3011, braslavs@ohio.edu; Andrea Gibson, director of research communications, (740) 597-2166, gibsona@ohio.edu.

[ | E-mail |

Share ]

Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

El Nino and a pathogen killed Costa Rican toad, study finds (PhysOrg)

Posted: 01 Mar 2010 12:03 PM PST

The role that climate change played in the toad's demise has been fiercely debated in recent years. The new paper, in the March 1 issue of the Proceedings of the National Academy of Sciences, is the latest to weigh in. In the study, researchers used old-growth trees from the Monteverde Cloud Forest Reserve to reconstruct moisture levels in that region over the last century. They expected to see global warming manifested in the form of a long-term warming or drying trend, but instead discovered that the forest's dry spells closely tracked El Niño, the periodic and natural warming of waters off South America that brings drought to some places and added rainfall and snow to others.

The golden toad vanished after an exceptionally dry season following the 1986-1987 El Niño, probably not long after the chytrid fungus was introduced. Scientists speculate that dry conditions caused the toads to congregate in a small number of puddles to reproduce, prompting the disease to spread rapidly. Some have linked the dry spell to global warming, arguing that warmer temperatures allowed the chytrid pathogen to flourish and weakened the toad's defenses. The new study finds that Monteverde was the driest it's been in a hundred years following the 1986-1987 El Niño, but that those dry conditions were still within the range of normal climate variability. The study does not address amphibian declines elsewhere, nor do the authors suggest that global warming is not a serious threat to biodiversity.

"There's no comfort in knowing that the golden toad's extinction was the result of El Niño and an introduced pathogen, because climate change will no doubt play a role in future extinctions," said study lead author Kevin Anchukaitis, a climate scientist at Columbia University's Lamont-Doherty Earth Observatory.

Average global temperatures have climbed about 0.8 degrees (1.4 degrees F) in the past hundred years, and some studies suggest that mountain regions are warming even more. In search of favorable conditions, alpine plants and animals are creeping to higher altitudes—not always with success.

In a 2006 paper in Nature, a team of U.S. and Latin American scientists linked rising tropical temperatures to the disappearance of 64 amphibian species in Central and South America. They proposed that warmer temperatures, associated with greater cloud cover, had led to cooler days and warmer nights, creating conditions that allowed the chytrid fungus to grow and spread. The fungus kills frogs and toads by releasing poison and attacking their skin and teeth. "Disease is the bullet killing frogs, but climate change is pulling the trigger," the lead author of the Nature study and a research scientist at the Monteverde reserve, J. Alan Pounds, said at the time.

The new study in PNAS suggests that it was El Niño—not climate change—that caused the fungus to thrive, killing the golden toad. "El Niño pulled the trigger," said Anchukaitis

Proving a link between climate change and biodiversity loss is difficult because so many overlapping factors may be at play, including habitat destruction, introduction of disease, pollution and normal weather variability. This is especially true in the tropics, because written weather records may go back only a few decades, preventing researchers from spotting long-term trends.

In the last decade, scientists have improved techniques for reconstructing past climate from tiny samples of wood drilled from tropical trees. Unlike trees in northern latitudes, tropical trees may grow year round, and often do not form the sharply defined growth rings that help scientists differentiate wet years from dry years in many temperate-region species. But even in the tropics, weather can leave an imprint on growing trees. During the dry season, trees take up water with more of the heavy isotope, oxygen-18, than oxygen-16. By analyzing the isotope ratio of the tree's wood, scientists can reconstruct the periods of rainfall and relative humidity throughout its life.

On two field trips to Costa Rica, Anchukaitis sampled nearly 30 trees, looking for specimens old enough, and with enough annual growth, to be studied. Back in the lab, he and study co-author Michael Evans, a climate scientist at University of Maryland, analyzed thousands of samples of wood trimmed to the size of pencil shavings.

Their results are only the latest challenge to the theory that climate change is driving the deadly chytrid outbreaks in the Americas. In a 2008 paper in the journal PLoS Biology, University of Maryland biologist Karen Lips mapped the loss of harlequin frogs from Costa Rica to Panama. She found that their decline followed the step-by-step pattern of an emerging infectious disease, affecting frogs in the mountains but not the lowlands. Had the outbreak been climate-induced, she said, the decline should have moved up and down the mountains over time.

Reached by e-mail, Pounds said he disagreed with the PNAS study. He said that his own 40-year rainfall and mist-cover measurements at Monteverde show a drying trend that the authors missed because they were unable to analyze moisture variations day to day or week to week. The weather is becoming more variable and extreme, he added, favoring some pathogens and making some animals more susceptible to disease.

"Anyone paying close attention to living systems in the wild is aware that our planet is in serious trouble," he said. "It's just a matter of time before this becomes painfully obvious to everyone."

Scientists think climate change may drive plants and animals to extinction by changing their habitats too quickly for them to adapt, shrinking water supplies, or by providing optimal conditions for diseases. Researchers have established links between population declines and global warming, from sea-ice dependent Adelie and emperor penguins, to corals threatened by ocean acidification and warming sea temperatures.

Warming ocean temperatures are likely to have some effect on El Niño, but scientists are still unsure what they will be, said Henry Diaz, an El Niño expert at the National Oceanographic and Atmospheric Agency. He said the paper offers strong evidence that climate change was not a factor in the El Niño dry season that coincided with the golden toad's extinction. "Climate change is best visualized as large-scale averages," he said. "Getting down to specific regions, Costa Rica, or the Monteverde cloud forest, it's hard to ascribe extinctions to climate change."

That does not mean humans are off the hook, said Evans. "Extinctions happen for reasons that are independent of human-caused climate change, but that does not mean human-caused climate change can't cause extinctions," he said.

Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

Study Techniques

Monday, March 1, 2010