[SN Today] from [Science News]
Isotope crisis threatens medical care
Global production of the feedstock for the leading medical-imaging isotope is low and erratic, putting health care in jeopardy.
By Janet Raloff
Web edition : Friday, August 14th, 2009
{Domestic source-to-be?
At 10 megawatts, the University of Missouri Research Reactor is the largest university research reactor in the country. Within two months, officials there will submit a proposal to the Energy Department to build a facility that would ultimately allow domestic production of a medical isotope that's currently in critically short supply.
University of Missouri Research Reactor}
Within the next two weeks, the vast majority of radioactive-imaging medical tests could be delayed or replaced by less desirable procedures. The reason: temporary shutdowns of Canadian and Dutch reactors that together normally provide some 70 percent of the world’s supplies of the isotope molybdenum-99 and at least 80 percent of North American supplies.
Each week, U.S. doctors prescribe some 300,000 medical-imaging tests that rely on technetium-99m, a radioactive isotope produced from molybdenum-99. About half of those tests measure heart function. Some map the spread of cancer. Others gauge the toxicity of cancer drugs on the circulatory system.
Neither the feedstock isotope nor the imaging isotope can be stockpiled because of their short radioactive half-lives (66 hours for molybdenum-99 and six hours for technetium-99m). New sources of molybdenum must be supplied to hospitals and imaging centers at least every two weeks.
“Right now, we’re managing [with the diminished supply], but just barely,” says Michael Graham, a nuclear medicine physician at the University of Iowa in Iowa City and president of the Society of Nuclear Medicine. “I’m concerned things are going to get worse by the end of this month.”
Indeed, “it’s predicted that in a week or 10 days, [U.S. supplies] could fall to perhaps 15 to 20 percent of our demand,” says Jeffrey Norenberg, director of radiopharmaceutical sciences at the University of New Mexico in Albuquerque and executive director of the National Association of Nuclear Pharmacies.
Five foreign reactors produce the vast majority of molybdenum-99. With an average age of 47 years — compared with an expected lifetime of only 35 years — those feedstock-producing reactors are all living on borrowed time. And they are subject to frequent outages for repairs.
The first reactor to go down this year was Canada’s 52-year-old National Research Universal reactor near Chalk River, in Ontario. On May 15, a small leak was identified in the reactor’s containment vessel.
That problem, initially expected to take perhaps a month to fix, is proving more difficult. An August 12 update by Atomic Energy of Canada Limited, which runs the facility, reports at least “nine sites likely requiring repair” and corrosion-fostered wall thinning and pitting of the reactor vessel. Currently, AECL now projects the reactor won’t return to service until at least the first quarter of 2010.
Almost two months to the day after AECL’s reactor went down, the 47-year-old Dutch High Flux Reactor in Petten began a month’s scheduled maintenance. That reactor should be back in service by the end of August. But delayed repairs of corrosion — which caused a temporary shutdown of the reactor last year — are slated to begin in February and last six months.
U.S. sources of molybdenum-99 have not existed since the mid-1980s. Concerned about the potential for catastrophic supply disruptions of this medical isotope, the Obama administration earlier this year “started plans to implement what we’re calling a long-term solution,” says Jean Cottom Allen in the White House Office of Science & Technology Policy. “We decided it was time to move forward, as quickly as we could, to establish domestic production capabilities.”
Within two weeks, she says, her office at OSTP also could have a blueprint for domestic supply strategies to implement during periods of crisis, such as next spring. That could prove a “much worse situation [than now],” Cottom Allen says, “because Petten will be down for much longer.”
Rapid evolution may be reshaping forest birds’ wings
Trend for pointier appendages in heavily logged boreal forests, with blunter, rounder ones in reforested parts of New England
By Susan Milius
Web edition : Friday, August 14th, 2009
{Wing shape-shifting
The hooded warbler is among the 21 bird species in a study of whether wing shape changed with forest cover during the past century. In the dwindling boreal forest, species in mature stands tended toward pointier wings, while in expanding New England woodlands species tended toward rounded wing tips.
USFWS}
PHILADELPHIA — When trees fall in the forest, unheard or not, they may change the shape of bird wings.
As logging whittled away at Canada’s vast boreal forest during the past century, bird species that frequent mature woodlands developed somewhat pointier wing tips, says André Desrochers of the Center for Forest Research at Laval University in Québec City.
During the same period, forests expanded in New England. Mature-woodland species there trended toward rounder wing tips, he reported August 13 in Philadelphia at a meeting of the American Ornithologists’ Union.
Sharper points on wings typically prove more efficient than blunter shapes during sustained flight, Desrochers says. But previous research on wing shapes and flight also found a cost for those points. On tight maneuvers threading 3-D mazes of branches, pointy wings lose out to rounder ones.
Several other studies have noted wing-shape differences within the same species if some populations migrate and some don’t. House finches in the eastern United States that follow the seasons, for example, tend toward sharper wings than western, couch-potato house finches.
Desrochers said he began to wonder whether human activities that leave forests in fragments might influence wings the same way migratory lifestyles do. Loggers chewing away at the conifer forest that once blanketed most of Canada has meant that birds now fly farther than their ancestors to find prime territories and mates. Feeding the relentless gaping mouths of chicks in tattered forests also meant longer commutes, and all this extra flying might change the balance of trade-offs for wing shape.
To see if a hundred years of landscape change could make a difference, Desrochers measured wings of 21 species of forest birds. He included species that are typical in early stages of forest growth and those more common in mature woodlands. Measuring a total of 851 specimens, he worked his way through the collections of the Canadian Museum of Nature in Gatineau, Quebec, and the Cornell Lab of Ornithology in Ithaca, N.Y.
Mature-woodland species showed the clearest change in pointiness regardless of body size, Desrochers said. During the past century, their long wing feathers, or primary feathers, overall gained about 2.23 millimeters on average. That uptick roughly matches the magnitude of differences between sexes. For example, a female boreal chickadee’s wing today is about the length of a male's in 1900, he said.
Desrochers also included more southerly species on his list, such as the scarlet tanager and hooded warbler. These birds had experienced a very different century. The landscape of New England, deforested during previous years, rebounded into green woodland again. And here, Desrochers found a trend back toward rounder wing tips. The eight mature-woodland species he studied typically had lost, on average, some 2.37 millimeters on those long primary feathers.
These species aren’t passive victims of environmental change, Desrochers said. As bird species face new challenges, they respond to the extent they can. "Birds are not like sitting ducks," he said.
“It’s surprising that there’s so much change so fast,” said ornithologist David Winkler, who studies physiological and evolutionary ecology at Cornell University.
He also noted that the study, which didn’t look at genetic evidence, doesn’t explicitly address whether the wings change by evolution or by some other process. Winkler said that in observing changes and invoking evolution, “we need to be careful.”
Desrochers responds that his approach can't prove the wing change is genetic. He points out, however, that research has found that inheritance strongly influences wing length, and he argues that rapid evolution is the most straightforward explanation for his findings.
Isotope crisis threatens medical care
Global production of the feedstock for the leading medical-imaging isotope is low and erratic, putting health care in jeopardy.
By Janet Raloff
Web edition : Friday, August 14th, 2009
{Domestic source-to-be?
At 10 megawatts, the University of Missouri Research Reactor is the largest university research reactor in the country. Within two months, officials there will submit a proposal to the Energy Department to build a facility that would ultimately allow domestic production of a medical isotope that's currently in critically short supply.
University of Missouri Research Reactor}
Within the next two weeks, the vast majority of radioactive-imaging medical tests could be delayed or replaced by less desirable procedures. The reason: temporary shutdowns of Canadian and Dutch reactors that together normally provide some 70 percent of the world’s supplies of the isotope molybdenum-99 and at least 80 percent of North American supplies.
Each week, U.S. doctors prescribe some 300,000 medical-imaging tests that rely on technetium-99m, a radioactive isotope produced from molybdenum-99. About half of those tests measure heart function. Some map the spread of cancer. Others gauge the toxicity of cancer drugs on the circulatory system.
Neither the feedstock isotope nor the imaging isotope can be stockpiled because of their short radioactive half-lives (66 hours for molybdenum-99 and six hours for technetium-99m). New sources of molybdenum must be supplied to hospitals and imaging centers at least every two weeks.
“Right now, we’re managing [with the diminished supply], but just barely,” says Michael Graham, a nuclear medicine physician at the University of Iowa in Iowa City and president of the Society of Nuclear Medicine. “I’m concerned things are going to get worse by the end of this month.”
Indeed, “it’s predicted that in a week or 10 days, [U.S. supplies] could fall to perhaps 15 to 20 percent of our demand,” says Jeffrey Norenberg, director of radiopharmaceutical sciences at the University of New Mexico in Albuquerque and executive director of the National Association of Nuclear Pharmacies.
Five foreign reactors produce the vast majority of molybdenum-99. With an average age of 47 years — compared with an expected lifetime of only 35 years — those feedstock-producing reactors are all living on borrowed time. And they are subject to frequent outages for repairs.
The first reactor to go down this year was Canada’s 52-year-old National Research Universal reactor near Chalk River, in Ontario. On May 15, a small leak was identified in the reactor’s containment vessel.
That problem, initially expected to take perhaps a month to fix, is proving more difficult. An August 12 update by Atomic Energy of Canada Limited, which runs the facility, reports at least “nine sites likely requiring repair” and corrosion-fostered wall thinning and pitting of the reactor vessel. Currently, AECL now projects the reactor won’t return to service until at least the first quarter of 2010.
Almost two months to the day after AECL’s reactor went down, the 47-year-old Dutch High Flux Reactor in Petten began a month’s scheduled maintenance. That reactor should be back in service by the end of August. But delayed repairs of corrosion — which caused a temporary shutdown of the reactor last year — are slated to begin in February and last six months.
U.S. sources of molybdenum-99 have not existed since the mid-1980s. Concerned about the potential for catastrophic supply disruptions of this medical isotope, the Obama administration earlier this year “started plans to implement what we’re calling a long-term solution,” says Jean Cottom Allen in the White House Office of Science & Technology Policy. “We decided it was time to move forward, as quickly as we could, to establish domestic production capabilities.”
Within two weeks, she says, her office at OSTP also could have a blueprint for domestic supply strategies to implement during periods of crisis, such as next spring. That could prove a “much worse situation [than now],” Cottom Allen says, “because Petten will be down for much longer.”
Rapid evolution may be reshaping forest birds’ wings
Trend for pointier appendages in heavily logged boreal forests, with blunter, rounder ones in reforested parts of New England
By Susan Milius
Web edition : Friday, August 14th, 2009
{Wing shape-shifting
The hooded warbler is among the 21 bird species in a study of whether wing shape changed with forest cover during the past century. In the dwindling boreal forest, species in mature stands tended toward pointier wings, while in expanding New England woodlands species tended toward rounded wing tips.
USFWS}
PHILADELPHIA — When trees fall in the forest, unheard or not, they may change the shape of bird wings.
As logging whittled away at Canada’s vast boreal forest during the past century, bird species that frequent mature woodlands developed somewhat pointier wing tips, says André Desrochers of the Center for Forest Research at Laval University in Québec City.
During the same period, forests expanded in New England. Mature-woodland species there trended toward rounder wing tips, he reported August 13 in Philadelphia at a meeting of the American Ornithologists’ Union.
Sharper points on wings typically prove more efficient than blunter shapes during sustained flight, Desrochers says. But previous research on wing shapes and flight also found a cost for those points. On tight maneuvers threading 3-D mazes of branches, pointy wings lose out to rounder ones.
Several other studies have noted wing-shape differences within the same species if some populations migrate and some don’t. House finches in the eastern United States that follow the seasons, for example, tend toward sharper wings than western, couch-potato house finches.
Desrochers said he began to wonder whether human activities that leave forests in fragments might influence wings the same way migratory lifestyles do. Loggers chewing away at the conifer forest that once blanketed most of Canada has meant that birds now fly farther than their ancestors to find prime territories and mates. Feeding the relentless gaping mouths of chicks in tattered forests also meant longer commutes, and all this extra flying might change the balance of trade-offs for wing shape.
To see if a hundred years of landscape change could make a difference, Desrochers measured wings of 21 species of forest birds. He included species that are typical in early stages of forest growth and those more common in mature woodlands. Measuring a total of 851 specimens, he worked his way through the collections of the Canadian Museum of Nature in Gatineau, Quebec, and the Cornell Lab of Ornithology in Ithaca, N.Y.
Mature-woodland species showed the clearest change in pointiness regardless of body size, Desrochers said. During the past century, their long wing feathers, or primary feathers, overall gained about 2.23 millimeters on average. That uptick roughly matches the magnitude of differences between sexes. For example, a female boreal chickadee’s wing today is about the length of a male's in 1900, he said.
Desrochers also included more southerly species on his list, such as the scarlet tanager and hooded warbler. These birds had experienced a very different century. The landscape of New England, deforested during previous years, rebounded into green woodland again. And here, Desrochers found a trend back toward rounder wing tips. The eight mature-woodland species he studied typically had lost, on average, some 2.37 millimeters on those long primary feathers.
These species aren’t passive victims of environmental change, Desrochers said. As bird species face new challenges, they respond to the extent they can. "Birds are not like sitting ducks," he said.
“It’s surprising that there’s so much change so fast,” said ornithologist David Winkler, who studies physiological and evolutionary ecology at Cornell University.
He also noted that the study, which didn’t look at genetic evidence, doesn’t explicitly address whether the wings change by evolution or by some other process. Winkler said that in observing changes and invoking evolution, “we need to be careful.”
Desrochers responds that his approach can't prove the wing change is genetic. He points out, however, that research has found that inheritance strongly influences wing length, and he argues that rapid evolution is the most straightforward explanation for his findings.
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