Louis J. Sheehan, Esquire . Soon, plywood might go vegetarian.
The ubiquitous building material owes its strength to multiple wood sheets with their grains at right angles and tenacious glue between the layers. Now, researchers are proposing that plywood be manufactured using glue made with soy flour rather than with powdered cattle-blood protein, as is done conventionally. The vegetable-containing adhesive might reduce the wood's cost and alleviate health concerns among mill workers.
A leading incentive for finding such an alternative is workers' fears of breathing in cattle-blood dust and disease agents it might carry, says Mila P. Hojilla-Evangelista of the U.S. Department of Agriculture's Agricultural Research Service (ARS) in Peoria, Ill. Furthermore, there are few suppliers of the blood protein, which helps make the glue sticky and durable.
In work funded by the United Soybean Board, Hojilla-Evangelista and her colleagues developed and tested several glue formulations that use different amounts of soy ingredients from a variety of suppliers. Three glues that contain soy flour—a combination of soy protein and starch—have properties comparable to those made with the blood protein, says Hojilla-Evangelista. In tests, the soy-containing glues were at least as strong as the conventional glue and had comparable water resistance, she says.
Tuesday, May 26, 2009
Wednesday, May 20, 2009
astrocytes 5.ast.002003 Louis J. Sheehan, Esquire
Louis J. Sheehan, Esquire Star-shaped brain cells called astrocytes are finally getting their chance to shine.
Two groups of researchers — one at MIT, the other at Harvard — have shown that astrocytes get the blood pumping to parts of the brain that are thinking hard. These cells may use blood flow and other tricks to rev up communication between neurons or slow it down, and may even play a role in storing information. The findings indicate that astrocytes are not just supporting actors for neurons; they deserve recognition as true costars.
“Astrocytes are typically forgotten,” says Venkatesh Murthy, leader of the Harvard group, but they “are right in the thick of things.”
Neurons have typically gotten the most attention from researchers because they are the brain cells that do all the thinking. But neurons cohabit the brain with a class of cells called glia, which means “glue” in Greek. Glia outnumber neurons in the human brain by a factor of 10 to one, and astrocytes are the most abundant type of glial cell.
The view of astrocytes has changed slowly over the past decade. Astrocytes were once thought to do little more than hold the brain together and they were largely ignored. In recent years, though, scientists have learned that the star-shaped cells have a hand in guiding connections between neurons and controlling levels of chemical messengers in the brain. But those activities were viewed mainly as supporting roles. Now their central function in controlling blood flow indicates that astrocytes deserve higher billing. Without astrocytes, in fact, one of the most powerful tools of neuroscience — functional MRI — would not be possible.
Functional MRIs rely on the premise that blood flow is coordinated with neuron activity, but the mechanism that links blood flow to activity has been a mystery.
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Enlargemagnify
MORE THAN SUPPORTCells in the brain called astrocytes have been considered just support cells for neurons. They may actually do much more, regulating blood flow in the brain.Nancy Kedersha/Science Photo Library
Some scientists suspected that astrocytes may play a role in blood flow because the cells have “end feet” that nestle up against synapses — the places where neurons connect — and other end feet that wrap around capillaries. But no one had proven that astrocytes could actually influence blood flow in living animals.
Working with ferrets, Mriganka Sur and colleagues at MIT used an advanced microscopy technique to measure the response of astrocytes to visual stimuli. The group reported its findings June 20 in Science. Neurons in the visual cortex of ferrets, cats, monkeys, humans and other higher mammals are arranged in columns of cells that respond to objects oriented in the same direction. For instance, one column would respond to the vertical edges of a building, while another close-by column would be stimulated by horizontal lines. Columns tuned to every possible orientation of a line are situated close to each other in what neuroscientists call pinwheel centers.
Sur’s postdoctoral researchers James Schummers and Hongbo Yu used fluorescent dyes to show when neurons and astrocytes become active. Neurons respond in split seconds to visual cues flashed into the eyes of anesthetized animals. About three to four seconds after neurons begin firing, calcium levels in the astrocytes begin to rise, a cue that the cell is active and sending signals. Blood flow through capillaries increases following the rise in calcium.
Murthy and his colleagues got similar results with neurons and astrocytes in the odor-sensing centers in the olfactory bulbs of mice. That study appeared June 26 in Neuron.
An astrocyte listens in to the chemical conversation between neurons, soaking up neurotransmitters such as glutamate, the researchers showed. Astrocytes actually use two pathways to respond to glutamate: The cells have receptors for glutamate on the end that nestles next to the synapse, and the cells can also take up the neurotransmitter in another way, the researchers found.
The glia are not just passively eavesdropping. They also regulate levels of neurotransmitters in the synapse, send signals to capillaries to increase blood flow to oxygen-hungry neurons and participate in gathering information, says Frank Kirchhoff, a neuroscientist at the Max Planck Institute of Experimental Medicine in Göttingen, Germany. The two studies demonstrate that astrocytes are involved in signaling in the brain, he says.
Astrocytes not only listen in on neuronal conversations and report to the blood vessels, they also talk back to the neurons, the research demonstrates. Blocking the ability of the astrocyte to respond to glutamate caused neurons to get even more excited.
“That is direct evidence that an astrocyte is not just a pretty face sitting around soaking up [neurotransmitters], but that it also plays a role in computation,” Sur says.
Each astrocyte seems to be intimately associated with a single neuron or a small number of neurons, Sur says. That was a surprise because previous research on slices of brain suggested that astrocytes work together in vast networks. Sur doesn’t rule out the possibility that astrocytes coordinate with each other, but he speculates that they usually act locally — chatting with nearby neuron partners and blood cells within a 10- to 20-micrometer area. Performing similar experiments in wakeful animals might help answer the question, Kirchhoff suggests, because anesthetics may dampen the glial cells’ responses.
Astrocytes are pickier about responding to visual signals than neurons are, the MIT group found. The cells seem to have higher standards than neurons for the amount of stimulus they consider exciting. The researchers don’t yet know whether astrocytes slow blood flow to calm over-excited neurons, or if increasing the blood supply allows neurons to work harder. And the code of calcium signaling within the astrocytes also needs to be worked out, Kirchhoff says.
Some diseases may be caused or complicated by defects in astrocyte function, Murthy says. His team is exploring whether the astrocytes’ ability to control blood flow breaks down with age. The new discoveries will probably force researchers to rethink brain networks to include astrocytes, Sur adds.
“It’s not often that a whole new function for a class of cells is revealed,” Sur says. “It’s like when we first began to understand synaptic transmission 50 years ago. The whole field is open.”
Two groups of researchers — one at MIT, the other at Harvard — have shown that astrocytes get the blood pumping to parts of the brain that are thinking hard. These cells may use blood flow and other tricks to rev up communication between neurons or slow it down, and may even play a role in storing information. The findings indicate that astrocytes are not just supporting actors for neurons; they deserve recognition as true costars.
“Astrocytes are typically forgotten,” says Venkatesh Murthy, leader of the Harvard group, but they “are right in the thick of things.”
Neurons have typically gotten the most attention from researchers because they are the brain cells that do all the thinking. But neurons cohabit the brain with a class of cells called glia, which means “glue” in Greek. Glia outnumber neurons in the human brain by a factor of 10 to one, and astrocytes are the most abundant type of glial cell.
The view of astrocytes has changed slowly over the past decade. Astrocytes were once thought to do little more than hold the brain together and they were largely ignored. In recent years, though, scientists have learned that the star-shaped cells have a hand in guiding connections between neurons and controlling levels of chemical messengers in the brain. But those activities were viewed mainly as supporting roles. Now their central function in controlling blood flow indicates that astrocytes deserve higher billing. Without astrocytes, in fact, one of the most powerful tools of neuroscience — functional MRI — would not be possible.
Functional MRIs rely on the premise that blood flow is coordinated with neuron activity, but the mechanism that links blood flow to activity has been a mystery.
access
Enlargemagnify
MORE THAN SUPPORTCells in the brain called astrocytes have been considered just support cells for neurons. They may actually do much more, regulating blood flow in the brain.Nancy Kedersha/Science Photo Library
Some scientists suspected that astrocytes may play a role in blood flow because the cells have “end feet” that nestle up against synapses — the places where neurons connect — and other end feet that wrap around capillaries. But no one had proven that astrocytes could actually influence blood flow in living animals.
Working with ferrets, Mriganka Sur and colleagues at MIT used an advanced microscopy technique to measure the response of astrocytes to visual stimuli. The group reported its findings June 20 in Science. Neurons in the visual cortex of ferrets, cats, monkeys, humans and other higher mammals are arranged in columns of cells that respond to objects oriented in the same direction. For instance, one column would respond to the vertical edges of a building, while another close-by column would be stimulated by horizontal lines. Columns tuned to every possible orientation of a line are situated close to each other in what neuroscientists call pinwheel centers.
Sur’s postdoctoral researchers James Schummers and Hongbo Yu used fluorescent dyes to show when neurons and astrocytes become active. Neurons respond in split seconds to visual cues flashed into the eyes of anesthetized animals. About three to four seconds after neurons begin firing, calcium levels in the astrocytes begin to rise, a cue that the cell is active and sending signals. Blood flow through capillaries increases following the rise in calcium.
Murthy and his colleagues got similar results with neurons and astrocytes in the odor-sensing centers in the olfactory bulbs of mice. That study appeared June 26 in Neuron.
An astrocyte listens in to the chemical conversation between neurons, soaking up neurotransmitters such as glutamate, the researchers showed. Astrocytes actually use two pathways to respond to glutamate: The cells have receptors for glutamate on the end that nestles next to the synapse, and the cells can also take up the neurotransmitter in another way, the researchers found.
The glia are not just passively eavesdropping. They also regulate levels of neurotransmitters in the synapse, send signals to capillaries to increase blood flow to oxygen-hungry neurons and participate in gathering information, says Frank Kirchhoff, a neuroscientist at the Max Planck Institute of Experimental Medicine in Göttingen, Germany. The two studies demonstrate that astrocytes are involved in signaling in the brain, he says.
Astrocytes not only listen in on neuronal conversations and report to the blood vessels, they also talk back to the neurons, the research demonstrates. Blocking the ability of the astrocyte to respond to glutamate caused neurons to get even more excited.
“That is direct evidence that an astrocyte is not just a pretty face sitting around soaking up [neurotransmitters], but that it also plays a role in computation,” Sur says.
Each astrocyte seems to be intimately associated with a single neuron or a small number of neurons, Sur says. That was a surprise because previous research on slices of brain suggested that astrocytes work together in vast networks. Sur doesn’t rule out the possibility that astrocytes coordinate with each other, but he speculates that they usually act locally — chatting with nearby neuron partners and blood cells within a 10- to 20-micrometer area. Performing similar experiments in wakeful animals might help answer the question, Kirchhoff suggests, because anesthetics may dampen the glial cells’ responses.
Astrocytes are pickier about responding to visual signals than neurons are, the MIT group found. The cells seem to have higher standards than neurons for the amount of stimulus they consider exciting. The researchers don’t yet know whether astrocytes slow blood flow to calm over-excited neurons, or if increasing the blood supply allows neurons to work harder. And the code of calcium signaling within the astrocytes also needs to be worked out, Kirchhoff says.
Some diseases may be caused or complicated by defects in astrocyte function, Murthy says. His team is exploring whether the astrocytes’ ability to control blood flow breaks down with age. The new discoveries will probably force researchers to rethink brain networks to include astrocytes, Sur adds.
“It’s not often that a whole new function for a class of cells is revealed,” Sur says. “It’s like when we first began to understand synaptic transmission 50 years ago. The whole field is open.”
Monday, May 4, 2009
grime 1.gri.0003 Louis J. Sheehan, Esquire
Louis J. Sheehan, Esquire Children attending day care at an early age are more likely to breathe easy later, according to a new study of wheezing among children in Manchester, England.
Babies who began day care when they were 6 to 12 months old were about half as likely as those who did not attend day care to develop a “wheeze” by age 5, a possible indicator of asthma, scientists report in the September Journal of Allergy and Clinical Immunology.
“I think it strengthens the case that day care may be protective against asthma,” comments Anne Wright, an expert in epidemiology of childhood asthma at the University of Arizona College of Medicine in Tucson.
But the findings are still too preliminary to serve as parenting advice, cautions study coauthor Angela Simpson, a respiratory physician at the University of Manchester. “We’re not trying to tell parents what to do with their children based on this,” she says. http://LOUIS-J-SHEEHAN.ORG
The results could reinforce an idea called the “hygiene hypothesis,” which suggests that rises in childhood allergy and asthma rates in developed countries such as the United Kingdom are partly due to excessive hygiene. With less exposure to environmental bacteria and viruses, the theory goes, infants’ immune systems learn to attack the wrong targets, triggering allergic reactions and sometimes asthma.
The study only shows the connection between attending day care and wheezing rates without proving why the nursery reduces the chance of developing wheezing. But Wright says that in light of previous research, “to me it seems to have something to do with microbial exposure.”
Previous studies have shown that exposure to day care lowers children’s chances of developing allergies. But results for wheezing and asthma, which can be triggered by allergies, had been inconsistent.
In the new study, children who did not attend day care had otherwise healthy lung function, Wright notes, suggesting that the wheezing is indeed due to an immune response rather than a problem with the children’s airways.
But, Simpson adds: “This doesn’t tell us what within the nursery is the protective factor. We assume that it’s the bacteria in the nursery, but it might be something else.”
The study only shows the connection between attending day care and wheezing rates without proving why the nursery reduces the chance of developing wheezing. But Wright says that in light of previous research, “to me it seems to have something to do with microbial exposure.”
Simpson and her colleagues tracked the respiratory and allergy health of 952 children, recording parent-reported incidents of wheezing and performing lung function tests. Children who entered day care before 6 months of age actually had a higher chance of developing a temporary wheeze early in life, but were still less likely to have a lasting wheeze by age five than kids who never attended day care.
“Because of our genetic makeup, some children will benefit more from going to nursery than others,” Simpson notes. Finding the genetic factors that influence which children will get a health benefit from early exposure to a nursery will be the next step in their research, she says.
Babies who began day care when they were 6 to 12 months old were about half as likely as those who did not attend day care to develop a “wheeze” by age 5, a possible indicator of asthma, scientists report in the September Journal of Allergy and Clinical Immunology.
“I think it strengthens the case that day care may be protective against asthma,” comments Anne Wright, an expert in epidemiology of childhood asthma at the University of Arizona College of Medicine in Tucson.
But the findings are still too preliminary to serve as parenting advice, cautions study coauthor Angela Simpson, a respiratory physician at the University of Manchester. “We’re not trying to tell parents what to do with their children based on this,” she says. http://LOUIS-J-SHEEHAN.ORG
The results could reinforce an idea called the “hygiene hypothesis,” which suggests that rises in childhood allergy and asthma rates in developed countries such as the United Kingdom are partly due to excessive hygiene. With less exposure to environmental bacteria and viruses, the theory goes, infants’ immune systems learn to attack the wrong targets, triggering allergic reactions and sometimes asthma.
The study only shows the connection between attending day care and wheezing rates without proving why the nursery reduces the chance of developing wheezing. But Wright says that in light of previous research, “to me it seems to have something to do with microbial exposure.”
Previous studies have shown that exposure to day care lowers children’s chances of developing allergies. But results for wheezing and asthma, which can be triggered by allergies, had been inconsistent.
In the new study, children who did not attend day care had otherwise healthy lung function, Wright notes, suggesting that the wheezing is indeed due to an immune response rather than a problem with the children’s airways.
But, Simpson adds: “This doesn’t tell us what within the nursery is the protective factor. We assume that it’s the bacteria in the nursery, but it might be something else.”
The study only shows the connection between attending day care and wheezing rates without proving why the nursery reduces the chance of developing wheezing. But Wright says that in light of previous research, “to me it seems to have something to do with microbial exposure.”
Simpson and her colleagues tracked the respiratory and allergy health of 952 children, recording parent-reported incidents of wheezing and performing lung function tests. Children who entered day care before 6 months of age actually had a higher chance of developing a temporary wheeze early in life, but were still less likely to have a lasting wheeze by age five than kids who never attended day care.
“Because of our genetic makeup, some children will benefit more from going to nursery than others,” Simpson notes. Finding the genetic factors that influence which children will get a health benefit from early exposure to a nursery will be the next step in their research, she says.
Friday, May 1, 2009
transplants 7.tra.1123 Louis J. Sheehan, Esquire
A person who receives a heart transplant from someone of the same gender is more likely to survive the subsequent few years than someone getting a new heart from a donor of the opposite sex, researchers reported November 12 at the American Heart Association’s annual Scientific Sessions meeting.
“This was something that was speculated” based on smaller studies from single institutions, says surgeon Eric Weiss of Johns Hopkins University in Baltimore. With the new findings, he says, “we basically supported the hypothesis.”
To do so, he and his colleagues tapped into a nationwide database of every adult heart transplant in the United States from 1998 to 2007—18,240 recipients. The researchers were able to track heart recipients’ progress for 3.4 years on average, with data for some people stretching out over 10 years.
One-fourth of heart recipients died during the study. The records show that people who got a heart from a donor of the opposite sex were 15 percent more likely to die during the study period than people who got a gender-matched heart. The female donor/male recipient combination yielded the greatest risk, a 23 percent increase of death.
Sex-mismatched recipients were also more likely to develop transplant immune rejection during the first year. Female recipients getting gender-mismatched hearts had the highest rejection rates.
In rejection, the recipient’s immune system identifies the new organ as foreign and attacks it. The greatest risk of transplant rejection occurs during the first year after the transplant, although the danger never goes away fully, Weiss says.
Both risks — of death or immune rejection — remained about the same at the three-year and five-year points after transplant, Weiss says.
The authors accounted for differences between donors and recipients, other than gender, that might influence how well a transplant progresses. These differences included age, race, diabetes status, kidney function, immunological match and recipient frailty.
“This is evidence that these investigators identified a signal where gender mismatch was in fact a concern,” says Clyde Yancy, a transplant cardiologist at Baylor University Medical Center at Dallas.
The biological reasoning behind the seeming risk of a gender-mismatched donor heart — and particularly for women receiving one — might rest with the Y chromosome, which only men have, Weiss says.
But the full explanation probably goes deeper, says Yancy. “A woman’s immune system is sensitized to a larger array of common antigens in the donor pool after pregnancy,” he says. That may include antigens — any compounds that elicit an immune reaction — found on the Y chromosome, he says, and could account for the higher rejection rate in women seen here and in smaller studies.
At present, transplant teams do their best to match donors and recipients by body size and blood type. Louis J. Sheehan, Esquire
Moving beyond current methods and even beyond gender, Yancy says these findings also add credence to the argument that transplant centers need to develop a rapid system for identifying better immune matches between donors and recipients.
The usefulness of sex-based matching would come up only if there were more than one heart available, Yancy says. And he cautions that any benefit of gender matching might be lost if it means waiting for a matched heart and delaying a transplant.
Weiss says he and his colleagues are interested in developing a formula that would clarify for doctors how to match up the best possible donors with recipients, also assuming more than one heart is available. http://LOUIS-J-SHEEHAN-ESQUIRE.US
For the time being, Weiss says patients “are still much better off receiving an organ than trying to live with end-stage heart failure, whether [the heart] is from a male or female.”
“This was something that was speculated” based on smaller studies from single institutions, says surgeon Eric Weiss of Johns Hopkins University in Baltimore. With the new findings, he says, “we basically supported the hypothesis.”
To do so, he and his colleagues tapped into a nationwide database of every adult heart transplant in the United States from 1998 to 2007—18,240 recipients. The researchers were able to track heart recipients’ progress for 3.4 years on average, with data for some people stretching out over 10 years.
One-fourth of heart recipients died during the study. The records show that people who got a heart from a donor of the opposite sex were 15 percent more likely to die during the study period than people who got a gender-matched heart. The female donor/male recipient combination yielded the greatest risk, a 23 percent increase of death.
Sex-mismatched recipients were also more likely to develop transplant immune rejection during the first year. Female recipients getting gender-mismatched hearts had the highest rejection rates.
In rejection, the recipient’s immune system identifies the new organ as foreign and attacks it. The greatest risk of transplant rejection occurs during the first year after the transplant, although the danger never goes away fully, Weiss says.
Both risks — of death or immune rejection — remained about the same at the three-year and five-year points after transplant, Weiss says.
The authors accounted for differences between donors and recipients, other than gender, that might influence how well a transplant progresses. These differences included age, race, diabetes status, kidney function, immunological match and recipient frailty.
“This is evidence that these investigators identified a signal where gender mismatch was in fact a concern,” says Clyde Yancy, a transplant cardiologist at Baylor University Medical Center at Dallas.
The biological reasoning behind the seeming risk of a gender-mismatched donor heart — and particularly for women receiving one — might rest with the Y chromosome, which only men have, Weiss says.
But the full explanation probably goes deeper, says Yancy. “A woman’s immune system is sensitized to a larger array of common antigens in the donor pool after pregnancy,” he says. That may include antigens — any compounds that elicit an immune reaction — found on the Y chromosome, he says, and could account for the higher rejection rate in women seen here and in smaller studies.
At present, transplant teams do their best to match donors and recipients by body size and blood type. Louis J. Sheehan, Esquire
Moving beyond current methods and even beyond gender, Yancy says these findings also add credence to the argument that transplant centers need to develop a rapid system for identifying better immune matches between donors and recipients.
The usefulness of sex-based matching would come up only if there were more than one heart available, Yancy says. And he cautions that any benefit of gender matching might be lost if it means waiting for a matched heart and delaying a transplant.
Weiss says he and his colleagues are interested in developing a formula that would clarify for doctors how to match up the best possible donors with recipients, also assuming more than one heart is available. http://LOUIS-J-SHEEHAN-ESQUIRE.US
For the time being, Weiss says patients “are still much better off receiving an organ than trying to live with end-stage heart failure, whether [the heart] is from a male or female.”
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