Festival organisers have chosen to host the European premiere of the Dickens classic directed by Mike Newell.
Newell, who previously directed Four Weddings and a Funeral, said: "I'm proud that our new version of Great Expectations should be presented this year, the bi-centenary of Dickens' birth.
"I've tried to make a film that is true to the theatrical vividness, energetic characters and high colour that he is loved for, while mining the deep seams of emotional cruelty and madness that underlie one of Dickens' darkest-shadowed stories.
"I've tried to make a film for a young modern audience in which Pip and Estella's fated love affair is shown through feelings and stresses that are of today and in a city that was, then, full of brawling energy, was unimaginably wealthy and very bad."
The story of orphan pip and his mysterious benefactor was most famously brought to life in 1946 by David Lean, but the new version has been highly anticipated with appearances from Helena Bonham Carter, David Walliams and Ralph Fiennes.
The cast also includes Robbie Coltrane, Ewen Bremner and Tamzin Outhwaite.
The event, formally known as the 56th BFI London Film Festival, will open with the European premiere of Tim Burton's Frankenweenie.
You should go all the way and consider a new house design for your next home renovation. The added expenses make all the difference, especially if you're forced to strip down the walls to expose and treat a pest infestation. Renovation projects involve several phases, but you can always hire someone to handle all the details, from the blueprint to the finishing touches. The design should be your priority, though, since all the other aspects comply with the floor plan. You don't have to hire an architect if you're only renovating the first floor or your backyard, but you'll need a good home builder who'll execute the details in time and within the quoted budget.
You can always look for home plans online if you're stuck with a tight budget. There are sites which let you download blueprints for a fee, which is recommended if you know a little about renovation and you're certain the specifications match with your project. A house designer can ensure the changes are structurally sound, though. He can also recommend themes that complement the houses in your neighborhood and your local climate. Many home designers also have connections to contractors and builders, so you'll likely get a good deal out of the referrals and packaged services your designer offers.
Having a floor plan and home design is but part of the process; the actual renovation will eat up most of your budget. Make sure you make the most out of the expenses and ask for detailed breakdown of the quote. Contractors usually offer ballpark quotes until you ask for specifics, especially if you're hiring their services to renovate your house and design it. A detailed quote usually comes with consultation fees, but the amount is a trifle compared to the inflated estimate you'll receive otherwise.
You still have to consider the variables of the project. If you want to include details which aren't covered by the recommendations, then you'll have to shoulder costs which exceed the quote. Most people insist on having their preferred bathroom or kitchen fixtures installed, especially if the package only includes stock installations. You can also cut down costs by choosing more affordable fixtures, like cedar cupboards instead of oak or mahogany, vinyl paneling instead of marble tiling. A fixed quote ensures you'll have everything covered so you can reallocate the expenses where these matter the most.
Builders also require slack to cover for expenses which can't be included in the quote. These are provisional costs determined during the renovation project, such as a structural flaw discovered on the foundation or the need to replace wall paneling that's crawling with black mold or termites. A provisional sum should be your builder's best guesstimate, and it shouldn't be confused with the ballpark quote of the initial consultation. Again, this provision works both ways. If the builder determines your house can do without aspects of renovation detailed on the fixed quote, then you're entitled to receive the corresponding credit and savings. Choosing house designs shouldn't be too difficult if you hire people who'll take over the small details. Hire the best designer and contractor and ensure your renovation is a worthwhile investment.
Consider house designs by Peter Downes if you?re looking for themes on your next renovation. House designers offer plans that make the most out of your floor space and climate, so choose consultation services and make your investment count.
Keywords: house designs, house and design, new house design, new home designs, house design
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Neuroscience just got faster, cheaper and easierPublic release date: 30-Aug-2012 [ | E-mail | Share ]
Contact: Marla Paul Marla-Paul@northwestern.edu 312-503-8928 Northwestern University
Asking 10 research questions instead of 100 gets same or better results
CHICAGO --- Richard Gershon has a shiny new toolbox for neuroscientists that will revolutionize their clinical research by making it radically faster, cheaper and more accurate. It also will help researchers recruit children and adults for studies because participation will be much less time consuming.
On Sept. 10 and 11, Gershon will introduce the new NIH Toolbox to hundreds of researchers at a special National Institutes of Health (NIH) conference in Bethesda, Maryland. At the end of September, he will give away the tools for free to NIH researchers.
Gershon, an associate professor of medical social sciences at Northwestern University Feinberg School of Medicine, has led an ambitious six-year NIH-funded study reflecting the efforts of 235 scientists around the world that provides the first common measurements for neurological and behavioral health. Currently, one researcher's test to measure depression, for example, isn't the same as another's, so their study results aren't comparable. Research is built on others' findings so this hodgepodge mires progress.
The 44 new tests --- available in Spanish and English --- slash the number of questions and time required for study participants by up to 90 percent. The tests also are royalty-free (other tests often have expensive royalties that hike the cost of research) and can be administered by anyone with a basic college education, a less expensive alternative to the Ph.D. level-person with specialized training now required to administer them.
An intelligence test that normally takes three hours is whipped off 30 in minutes with the new NIH Toolbox version. Many traditional "gold standard" tests are trimmed from 30 items to five. Every new test was validated to make sure it yields comparable or better results than the longer ones.
Many of the streamlined tests are accomplished through computer adaptive testing - Gershon's expertise. In this approach, the computer is constantly adjusting the questions to meet the level of the person being tested, eliminating lots of extraneous questions.
"With the computer we cut to what we need to measure in each individual person," Gershon said. "We zero in on that person's individual level of functioning and don't waste their time asking questions far above or below their ability."
Scientists collected data from more than 20,000 participants to determine the difficulty level of every item and validate those items against "gold standard" measures.
This is how it works. In a vocabulary test administered to a third grader, the first item will be third grade level. If the student gets that correct, the next one will be 3.5 level and so forth until the computer has zeroed in on the student's precise ability level. The test only has 20 vocabulary questions compared to the traditional 50 items, but the shorter test is more reliable because half the items on the traditional test would be below the student's ability and half would be above it.
The shortened tests will aid a longitudinal study like the 100,000-subject National Children's Study, which can spend only so much time testing each child. "Even if we can only test a child for one hour every year we now can administer up to 20 tests during that hour and accurately track his or her development," Gershon said.
The new tests also are the first to measure a continuum of health from dysfunction through superfunction in neurological and behavioral health for persons ages 3 to 85. Most existing tests were developed to measure dysfunction A benefit of the continuum is being able to identify --- in longitudinal studies, epidemiological studies and clinical trials --- where problems begin to emerge and what the causes may be. To develop norms for the continuum, researchers measured a sample of 5,000 people in English and Spanish of various races and ethnicities of every age in 10 different data collection sites around the country.
Gershon tapped the top scientists in the country in each domain to develop the new tests. For the olfaction measure, eight top researchers conferred to examine the worldwide inventory of smell tests and eventually designed their own. The NIH version costs $2 a person (to pay for the scratch and sniff cards) compared to the gold standard tests, which are available for $15 to $30.
In addition to smell, some of the measures include multiple areas of cognition, emotional health and motor and sensory functioning such as vision and hearing.
More than 30 Northwestern scientists and staff members were involved in the NIH Toolbox including David Cella, chair of medical social sciences, and senior researchers Sandra Weintraub, William Rymer, Nina Kraus and Steve Zecker.
###
This project is supported by federal funds from the Blueprint for Neuroscience Research and the Office of Behavioral and Social Sciences Research, National Institutes of Health, under Contract No. HHS-N-260-2006-00007-C.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Neuroscience just got faster, cheaper and easierPublic release date: 30-Aug-2012 [ | E-mail | Share ]
Contact: Marla Paul Marla-Paul@northwestern.edu 312-503-8928 Northwestern University
Asking 10 research questions instead of 100 gets same or better results
CHICAGO --- Richard Gershon has a shiny new toolbox for neuroscientists that will revolutionize their clinical research by making it radically faster, cheaper and more accurate. It also will help researchers recruit children and adults for studies because participation will be much less time consuming.
On Sept. 10 and 11, Gershon will introduce the new NIH Toolbox to hundreds of researchers at a special National Institutes of Health (NIH) conference in Bethesda, Maryland. At the end of September, he will give away the tools for free to NIH researchers.
Gershon, an associate professor of medical social sciences at Northwestern University Feinberg School of Medicine, has led an ambitious six-year NIH-funded study reflecting the efforts of 235 scientists around the world that provides the first common measurements for neurological and behavioral health. Currently, one researcher's test to measure depression, for example, isn't the same as another's, so their study results aren't comparable. Research is built on others' findings so this hodgepodge mires progress.
The 44 new tests --- available in Spanish and English --- slash the number of questions and time required for study participants by up to 90 percent. The tests also are royalty-free (other tests often have expensive royalties that hike the cost of research) and can be administered by anyone with a basic college education, a less expensive alternative to the Ph.D. level-person with specialized training now required to administer them.
An intelligence test that normally takes three hours is whipped off 30 in minutes with the new NIH Toolbox version. Many traditional "gold standard" tests are trimmed from 30 items to five. Every new test was validated to make sure it yields comparable or better results than the longer ones.
Many of the streamlined tests are accomplished through computer adaptive testing - Gershon's expertise. In this approach, the computer is constantly adjusting the questions to meet the level of the person being tested, eliminating lots of extraneous questions.
"With the computer we cut to what we need to measure in each individual person," Gershon said. "We zero in on that person's individual level of functioning and don't waste their time asking questions far above or below their ability."
Scientists collected data from more than 20,000 participants to determine the difficulty level of every item and validate those items against "gold standard" measures.
This is how it works. In a vocabulary test administered to a third grader, the first item will be third grade level. If the student gets that correct, the next one will be 3.5 level and so forth until the computer has zeroed in on the student's precise ability level. The test only has 20 vocabulary questions compared to the traditional 50 items, but the shorter test is more reliable because half the items on the traditional test would be below the student's ability and half would be above it.
The shortened tests will aid a longitudinal study like the 100,000-subject National Children's Study, which can spend only so much time testing each child. "Even if we can only test a child for one hour every year we now can administer up to 20 tests during that hour and accurately track his or her development," Gershon said.
The new tests also are the first to measure a continuum of health from dysfunction through superfunction in neurological and behavioral health for persons ages 3 to 85. Most existing tests were developed to measure dysfunction A benefit of the continuum is being able to identify --- in longitudinal studies, epidemiological studies and clinical trials --- where problems begin to emerge and what the causes may be. To develop norms for the continuum, researchers measured a sample of 5,000 people in English and Spanish of various races and ethnicities of every age in 10 different data collection sites around the country.
Gershon tapped the top scientists in the country in each domain to develop the new tests. For the olfaction measure, eight top researchers conferred to examine the worldwide inventory of smell tests and eventually designed their own. The NIH version costs $2 a person (to pay for the scratch and sniff cards) compared to the gold standard tests, which are available for $15 to $30.
In addition to smell, some of the measures include multiple areas of cognition, emotional health and motor and sensory functioning such as vision and hearing.
More than 30 Northwestern scientists and staff members were involved in the NIH Toolbox including David Cella, chair of medical social sciences, and senior researchers Sandra Weintraub, William Rymer, Nina Kraus and Steve Zecker.
###
This project is supported by federal funds from the Blueprint for Neuroscience Research and the Office of Behavioral and Social Sciences Research, National Institutes of Health, under Contract No. HHS-N-260-2006-00007-C.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Contact: Andrew Myers admyers@stanford.edu 650-736-2245 Stanford School of Engineering
Stanford electrical engineers overturn existing models to demonstrate the feasibility of a millimeter-sized, wirelessly powered cardiac device
A team of engineers at Stanford has demonstrated the feasibility of a super-small, implantable cardiac device that gets its power not from batteries, but from radio waves transmitted from outside the body. The implanted device is contained in a cube just eight-tenths of a millimeter in radius. It could fit on the head of pin.
The findings were published in the journal Applied Physics Letters. In their paper, the researchers demonstrated wireless power transfer to a millimeter-sized device implanted five centimeters inside the chest on the surface of the hearta depth once thought out of reach for wireless power transmission.
The paper's senior author was Ada Poon, a professor of electrical engineering at Stanford. Sanghoek Kim and John Ho, both doctoral candidates in Poon's lab, were first authors.
The engineers say the research is a major step toward a day when all implants are driven wirelessly. Beyond the heart, they believe such devices might include swallowable endoscopesso-called "pillcams" that travel the digestive tractpermanent pacemakers and precision brain stimulators; virtually any medical applications where device size and power matter.
A revolution in the body
Implantable medical devices in the human body have revolutionized medicine. Hundreds of thousands if not millions of pacemakers, cochlear implants and drug pumps are today helping people live relatively normal lives, but these devices are not without engineering challenges.
First off, they require power, which means batteries, and batteries are bulky. In a device like a pacemaker, the battery alone accounts for as much as half the volume of the device it drives. Second, batteries have finite lives. New surgery is needed when they wane.
"Wireless power solves both challenges," said Poon.
Last year, Poon made headlines when she demonstrated a wirelessly powered, self-propelled device capable of swimming through the bloodstream. To get there she needed to overturn some long-held assumptions about delivery of wireless power through the human body.
Her device works by a combination inductive and radiative transmission of power. Both are types of electromagnetic transfer in which a transmitter sends radio waves to a coil of wire inside the body. The radio waves produce an electrical current in the coil sufficient to operate a small device.
There is an indirect relationship between the frequency of the transmitted radio waves and the size of the receive antenna. That is, to deliver a desired level of power, lower frequency waves require bigger coils. Higher frequency waves can work with smaller coils.
"For implantable medical devices, therefore, the goal is a high-frequency transmitter and a small receiver, but there is one big hurdle," explained Kim.
Ignoring consensus
Existing mathematical models have held that high frequency radio waves do not penetrate far enough into human tissue, necessitating the use of low-frequency transmitters and large antennastoo large to be practical for implantable devices.
Ignoring the consensus, Poon proved the models wrong. Human tissue dissipates electric fields quickly, it is true, but radio waves can travel in a different wayas alternating waves of electric and magnetic fields. With the correct equations in hand, she discovered that high-frequency signals travel much deeper than anyone suspected.
"In fact, to achieve greater power efficiency, it is actually advantageous that human tissue is a very poor electrical conductor," said Kim. "If it were a good conductor, it would absorb energy, create heating and prevent sufficient power from reaching the implant."
According to their revised models, the researchers found that the maximum power transfer through human tissue occurs at about 1.7 billion cycles per second.
"In this high-frequency range, we can increase power transfer by about ten times over earlier devices," said Ho, who honed the mathematical models.
The discovery meant that the team could shrink the receive antenna by a factor of ten as well, to a scale that makes wireless implantable devices feasible. At that the optimal frequency, a millimeter-radius coil is capable of harvesting more than 50 microwatts of power, well in excess of the needs of a recently demonstrated eight-microwatt pacemaker.
Additional challenges
With the dimensional challenges solved, the team found themselves bound in by other engineering constraints. First, electronic medical devices must meet stringent health standards established by the IEEE, particularly with regard to tissue heating. Second, the team found that receive and transmit antennas had to be optimally oriented to achieve maximum efficiency. Differences in alignment of just a few degrees could produce troubling drops in power.
"This can't happen with medical devices," said Poon. "As the human heart and body are in constant motion, solving this issue was critical to the success of our research."
The team responded by designing an innovative slotted transmit antenna structure. It delivers consistent power efficiency regardless of orientation of the two antennas.
The new design serves additionally to focus the radio waves precisely at the point inside the body where the implanted device rests on the surface of the heart, increasing the electric field where it is needed most, but canceling it elsewhere. This helps reduce overall tissue heating to levels well within the IEEE standards. Poon has applied for a patent for the antenna structure.
###
This research was made possible by funding from the C2S2 Focus Center, one of six research centers funded under the Focus Center Research Program (FCRP), a Semiconductor Research Corporation entity. Lisa Chen also contributed to this study.
This article was written by Andrew Myers, associate director of communications for the Stanford University School of Engineering.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Contact: Andrew Myers admyers@stanford.edu 650-736-2245 Stanford School of Engineering
Stanford electrical engineers overturn existing models to demonstrate the feasibility of a millimeter-sized, wirelessly powered cardiac device
A team of engineers at Stanford has demonstrated the feasibility of a super-small, implantable cardiac device that gets its power not from batteries, but from radio waves transmitted from outside the body. The implanted device is contained in a cube just eight-tenths of a millimeter in radius. It could fit on the head of pin.
The findings were published in the journal Applied Physics Letters. In their paper, the researchers demonstrated wireless power transfer to a millimeter-sized device implanted five centimeters inside the chest on the surface of the hearta depth once thought out of reach for wireless power transmission.
The paper's senior author was Ada Poon, a professor of electrical engineering at Stanford. Sanghoek Kim and John Ho, both doctoral candidates in Poon's lab, were first authors.
The engineers say the research is a major step toward a day when all implants are driven wirelessly. Beyond the heart, they believe such devices might include swallowable endoscopesso-called "pillcams" that travel the digestive tractpermanent pacemakers and precision brain stimulators; virtually any medical applications where device size and power matter.
A revolution in the body
Implantable medical devices in the human body have revolutionized medicine. Hundreds of thousands if not millions of pacemakers, cochlear implants and drug pumps are today helping people live relatively normal lives, but these devices are not without engineering challenges.
First off, they require power, which means batteries, and batteries are bulky. In a device like a pacemaker, the battery alone accounts for as much as half the volume of the device it drives. Second, batteries have finite lives. New surgery is needed when they wane.
"Wireless power solves both challenges," said Poon.
Last year, Poon made headlines when she demonstrated a wirelessly powered, self-propelled device capable of swimming through the bloodstream. To get there she needed to overturn some long-held assumptions about delivery of wireless power through the human body.
Her device works by a combination inductive and radiative transmission of power. Both are types of electromagnetic transfer in which a transmitter sends radio waves to a coil of wire inside the body. The radio waves produce an electrical current in the coil sufficient to operate a small device.
There is an indirect relationship between the frequency of the transmitted radio waves and the size of the receive antenna. That is, to deliver a desired level of power, lower frequency waves require bigger coils. Higher frequency waves can work with smaller coils.
"For implantable medical devices, therefore, the goal is a high-frequency transmitter and a small receiver, but there is one big hurdle," explained Kim.
Ignoring consensus
Existing mathematical models have held that high frequency radio waves do not penetrate far enough into human tissue, necessitating the use of low-frequency transmitters and large antennastoo large to be practical for implantable devices.
Ignoring the consensus, Poon proved the models wrong. Human tissue dissipates electric fields quickly, it is true, but radio waves can travel in a different wayas alternating waves of electric and magnetic fields. With the correct equations in hand, she discovered that high-frequency signals travel much deeper than anyone suspected.
"In fact, to achieve greater power efficiency, it is actually advantageous that human tissue is a very poor electrical conductor," said Kim. "If it were a good conductor, it would absorb energy, create heating and prevent sufficient power from reaching the implant."
According to their revised models, the researchers found that the maximum power transfer through human tissue occurs at about 1.7 billion cycles per second.
"In this high-frequency range, we can increase power transfer by about ten times over earlier devices," said Ho, who honed the mathematical models.
The discovery meant that the team could shrink the receive antenna by a factor of ten as well, to a scale that makes wireless implantable devices feasible. At that the optimal frequency, a millimeter-radius coil is capable of harvesting more than 50 microwatts of power, well in excess of the needs of a recently demonstrated eight-microwatt pacemaker.
Additional challenges
With the dimensional challenges solved, the team found themselves bound in by other engineering constraints. First, electronic medical devices must meet stringent health standards established by the IEEE, particularly with regard to tissue heating. Second, the team found that receive and transmit antennas had to be optimally oriented to achieve maximum efficiency. Differences in alignment of just a few degrees could produce troubling drops in power.
"This can't happen with medical devices," said Poon. "As the human heart and body are in constant motion, solving this issue was critical to the success of our research."
The team responded by designing an innovative slotted transmit antenna structure. It delivers consistent power efficiency regardless of orientation of the two antennas.
The new design serves additionally to focus the radio waves precisely at the point inside the body where the implanted device rests on the surface of the heart, increasing the electric field where it is needed most, but canceling it elsewhere. This helps reduce overall tissue heating to levels well within the IEEE standards. Poon has applied for a patent for the antenna structure.
###
This research was made possible by funding from the C2S2 Focus Center, one of six research centers funded under the Focus Center Research Program (FCRP), a Semiconductor Research Corporation entity. Lisa Chen also contributed to this study.
This article was written by Andrew Myers, associate director of communications for the Stanford University School of Engineering.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Wall Street is a funny place, with its inverse indicators, relative outperformance, and discounting mechanisms that often predigest good and bad news before it happens. And so it almost seems fitting that a week after the S&P 500 touched a 4-year high - then failed to follow through - the stock-buying community is a tad nervous about getting in on a rally that began in early June.
What's worse, even though a dollar's worth of earnings costs 15% less today than it did at the top of the market five years ago, investors are still not moved to act on this theoretical sale or value.
"Cheap implies that going forward you're going to make money and that's the big question right now," says Tom Lydon, the editor of ETF Trends.com in the attached video. "There's lots to be uncertain about," he says what with the weather, the Fed, political conventions, the upcoming jobs report, and the ongoing mess that is Europe right now.
As much as Lydon says the S&P, at 12.7x forward earnings today is ''relatively cheap" compared to the 15.1x that investors were paying at the tippy-top in 2007, investors are disenchanted with stocks and taking money out.
"One thing that we're looking at is, are investors looking for information?" Lydon says. "Surprisingly, ETF-related searches (on the internet) are down 50% from this time a year ago, so it's amazing how the average investor really is not engaged or confident about the market going forward."
Of course, that hesitancy or disbelief could be a good sign - to a point.
"For us to make that next 11% climb from where we are right now in the S&P, to hit a new high where we were in 2007, the average investor is going to have to get engaged," Lydon says, and so-called ''cheapness" does not appear to be the motivating force.
What about you? Are you along for the ride, eying the exits or waiting for a pullback?
The e-book vs. real-book debate is very much a matter of opinion, so it's only fitting that the two learn to get along. Kobo and the American Booksellers Association seem to think so too, which is why they are teaming up to bring the Kobo's devices, accessories and virtual shelves to independent bookstores across America. Around 2,000 indie retailers are included in the plan, with the first 400 expected to get tooled and trained this fall. Although the stores will take a cut of Kobo's sales, we can't see any long-term benefits for them, but what do you make of the increasing physical presence of e-readers? Is it a move towards peaceful co-existence, or a case of "keep my enemy closer"?
ScienceDaily (Aug. 30, 2012) ? The skin, the blood, and the lining of the gut -- adult stem cells replenish them daily. But stem cells really show off their healing powers in planarians, humble flatworms fabled for their ability to rebuild any missing body part. Just how adult stem cells build the right tissues at the right times and places has remained largely unanswered.
Now, in a study published in an upcoming issue of Development, researchers at the Stowers Institute for Medical Research describe a novel system that allowed them to track stem cells in the flatworm Schmidtea mediterranea. The team found that the worms' stem cells, known as neoblasts, march out, multiply, and start rebuilding tissues lost to amputation.
"We were able to demonstrate that fully potent stem cells can mobilize when tissues undergo structural damage," says Howard Hughes Medical Institute and Stowers Investigator Alejandro S?nchez Alvarado, Ph.D., who led the study. "And these processes are probably happening to both you and me as we speak, but are very difficult to visualize in organisms like us."
Stem cells hold the potential to provide an unlimited source of specialized cells for regenerative therapy of a wide variety of diseases but delivering human stem cell therapies to the right location in the body remains a major challenge. The ability to follow individual neoblasts opens the door to uncovering the molecular cues that help planarian stem cells navigate to the site of injury and ultimately may allow scientists to provide therapeutic stem cells with guideposts to their correct destination.
"Human counterparts exist for most of the genes that we have found to regulate the activities of planarian stem cells," says S?nchez Alvarado. "But human beings have these confounding levels of complexity. Planarians are much simpler making them ideal model systems to study regeneration."
Scientists had first hypothesized in the late 1800s that planarian stem cells, which normally gather near the worms' midlines, can travel toward wounds. The past century produced evidence both for and against the idea. S?nchez Alvarado, armed with modern tools, decided to revisit the question.
For the new study, first author Otto C. Guedelhoefer, IV, Ph.D., a former graduate student in S?nchez Alvarado's lab, exposed S. mediterranea to radiation, which killed the worms' neoblasts while leaving other types of cells unharmed. The irradiated worms would wither and die within weeks unless Guedelhoefer transplanted some stem cells from another worm. The graft's stem cells sensed the presence of a wound -- the transplant site -- migrated out of the graft, reproduced and rescued their host. Unlike adult stem cells in humans and other mammals, planarian stem cells remain pluripotent in fully mature animals and remain so even as they migrate.
But when Guedelhoefer irradiated only a part of the worm's body, the surviving stem cells could not sense the injury and did not mobilize to fix the damage, which showed that the stem cells normally stay in place. Only when a fair amount of irradiated tissue died did the stem cells migrate to the injured site and start to rebuild. Next, Guedelhoefer irradiated a worm's body part and cut it with a blade. The surviving stem cells arrived at the scene within days.
To perform the experiments, Guedelhoefer adapted worm surgery and x-ray methods created sixty to ninety years ago. "Going back to the old literature was essential and saved me tons of time," says Guedelhoefer, currently a postdoctoral fellow at the University of California, Santa Barbara. He was able to reproduce and quantify results obtained in 1949 by F. Dubois, a French scientist, who first developed the techniques for partially irradiating planarians with x-rays.
But Guedelhoefer went further. He pinpointed the locations of stem cells and studied how far they dispersed using RNA whole-mount in situ hybridization (WISH), specifically adapted to planarians in S?nchez Alvarado's lab. Using WISH, he observed both original stem cells and their progeny by tagging specific pieces of mRNA . The technique allowed him to determine that pluripotent stem cells can travel and produce different types of progeny at the same time.
"In other systems, most migrating stem cell progeny are not pluripotent," says Guedelhoefer. "For the most part, blood stem cells in humans stay in the bone marrow but their progeny leave and turn into a few other cell types." But in planarians, it looks like those two things are completely separate. Stem cells can move and maintain the full potential to turn into other types of cells."
Next, S?nchez Alvarado looks forward to implementing genetic screens and transplantation experiments to disrupt or enhance the cellular behaviors the team observed, to figure out the "rules of engagement" for stem cell migration, he says.
"Why can some animals regenerate whole body parts but you and I are not good at it?" says S?nchez Alvarado. "Can we write an extra rule or erase one? Is it possible, for instance, to get rid of cancer while gaining regenerative properties? These are questions we'd love to have answers to."
The Stowers Institute for Medical Research, a National Institutes of Health Training Grant (5T32 HD0791), a National Institutes of Health Grant (GM057260), and Howard Hughes Medical Institute provided funding for this work.
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The above story is reprinted from materials provided by Stowers Institute for Medical Research, via Newswise.
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Journal Reference:
O. C. Guedelhoefer, A. S. Alvarado. Amputation induces stem cell mobilization to sites of injury during planarian regeneration. Development, 2012; DOI: 10.1242/dev.082099
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.
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Public release date: 30-Aug-2012
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