PHILADELPHIA, A survey of 4,193 men living in New York City conducted by the New York City Department of Health and Mental Hygiene found that nearly 10 percent of male participants who identified themselves as straight reported having sex with at least one man during the previous year.
The study, "Discordance between Sexual Behavior and Self-Reported Sexual Identity: A Population-Based Survey of New York City Men," is published in the Sept. 19, 2006, issue of Annals of Internal Medicine.
Compared to men who identified themselves as gay, these men were more likely to belong to a minority racial or ethnic group, be foreign-born, have a lower educational level, and live outside Manhattan. Seventy percent reported being married. This group also was less likely to have been tested for HIV infection during the previous year and less likely to have used a condom during the last sexual encounter than men who identified themselves as gay.
"Doctors need to ask patients about specific sexual practices instead of relying on self-reported sexual orientation to assess risk for unsafe sexual practices and risk for sexually transmitted diseases," said Preeti Pathela, DrPH, lead author of the study. "Public health prevention messages should target risky sexual activities, such as unprotected receptive anal sex, and should not be framed to appeal solely to gay-identified men."
This study is one of the largest U.S. population-based surveys to report on the contrast between a man's self-identified sexual identity and his actual sexual behaviors.
Contact: Steve Majewski
smajewski@acponline.org
215-351-2514
American College of Physicians
Monday, November 20, 2006
Tuesday, October 03, 2006
Exam nerves affects students' immune defense
It is hardly surprising that one of the medical programmes most important exams is stressful for students. However, research now shows that this mental stress also affects the students' immune defense systems, particularly amongst those suffering from allergies.
While diseases like asthma and allergies are becoming increasingly common in the West, many people believe that we are living ever stressful lives. A new study from Karolinska Institutet (KI) in Sweden backs up what many people have suspected: that there are important links between mental stress and the complex physical inflammation reactions characteristic of allergies.
In order to understand the link between stress and allergy, the scientists have examined how a major medical exam at KI affects feelings of stress, stress hormone levels, the immune system and lung function amongst students with and without allergies. The extensive tests were made on two occasions, first with the students during a calm period of study with no exam in sight, and then shortly before a major exam. Twenty two students with hayfever and/or asthma and 19 healthy students took part.
Press Release Gold - Daily Digest on Science & Technology
For the first time on record, scientists were able to show that a group of cells that are central to the human immune system known as regulatory T cells appear to increase sharply in number in response to mental stress. A regulatory T cell is a kind of white blood cell that controls the activity of a number of other types of immune cell. This increase was observed in both groups of students.
The study also showed that blood concentrations of a group of inflammation products called cytokines had changed and shifted against a pattern associated with allergic inflammation in the allergic students, but remained normal in the healthy students.
According to Mats Lekander and Caroline Olgart Höglund, who are leading the research group, the two discoveries might very well be linked.
"There is much to suggest that the regulatory T cells are dysfunctional in people with allergies," he says. When people become stressed, they increase in number and normally have an anti-inflammatory effect. If this system does not work in people with allergies, it could explain the changed cytokine balance that we have observed in them."
Contact: Katarina Sternudd
katarina.sternudd@ki.se
46-852-483-895
Karolinska Institutet
While diseases like asthma and allergies are becoming increasingly common in the West, many people believe that we are living ever stressful lives. A new study from Karolinska Institutet (KI) in Sweden backs up what many people have suspected: that there are important links between mental stress and the complex physical inflammation reactions characteristic of allergies.
In order to understand the link between stress and allergy, the scientists have examined how a major medical exam at KI affects feelings of stress, stress hormone levels, the immune system and lung function amongst students with and without allergies. The extensive tests were made on two occasions, first with the students during a calm period of study with no exam in sight, and then shortly before a major exam. Twenty two students with hayfever and/or asthma and 19 healthy students took part.
Press Release Gold - Daily Digest on Science & Technology
For the first time on record, scientists were able to show that a group of cells that are central to the human immune system known as regulatory T cells appear to increase sharply in number in response to mental stress. A regulatory T cell is a kind of white blood cell that controls the activity of a number of other types of immune cell. This increase was observed in both groups of students.
The study also showed that blood concentrations of a group of inflammation products called cytokines had changed and shifted against a pattern associated with allergic inflammation in the allergic students, but remained normal in the healthy students.
According to Mats Lekander and Caroline Olgart Höglund, who are leading the research group, the two discoveries might very well be linked.
"There is much to suggest that the regulatory T cells are dysfunctional in people with allergies," he says. When people become stressed, they increase in number and normally have an anti-inflammatory effect. If this system does not work in people with allergies, it could explain the changed cytokine balance that we have observed in them."
Contact: Katarina Sternudd
katarina.sternudd@ki.se
46-852-483-895
Karolinska Institutet
Saturday, September 23, 2006
Encoded metallic nanowires reveal bioweapons
Striped nanowires of silver and gold for parallel detection of various pathogens
When dangerous infectious diseases or biological weapons are suspected, fast help is required. The first step is a reliable, sensitive, and unambiguous, yet also fast and simple, identification of the pathogen; preferably, this test should be carried out on the spot, not in a laboratory. Portable miniature biodetection systems that can detect multiple pathogens simultaneously would be ideal for this task. American researchers from Lawrence Livermore National Laboratory led by Jeffrey Tok, in collaboration with groups at Stanford University, University of California at Davis, and Oxonica Inc (formerly Nanoplex Technologies Inc). have now developed a new basis for such a multiplex device: they are using silver and gold "striped" nanowires as supports for simultaneous immunological tests for various pathogens. Individual patterns of stripes act in the role of "barcodes". These "nanobarcoded" particles are manufactured by Oxonica Inc using template-assisted electrochemical deposition of metals within the tiny cylindrical pores of alumina membranes. When deposited gold and silver are alternated in a defined way, nanowires with different characteristic stripe patterns are produced. The pattern of optical reflections from each sequence of stripes can later be unambiguously recognized--just like a barcode.
Antibodies aimed at specific pathogens can be attached to these wires. For their test runs, Tok and his colleagues selected harmless model substances to stand in for anthrax spores, smallpox virus, and protein toxins such as ricin and botulinum toxin. If a simultaneous test for all of these is desired, the anthrax antibody would be attached to stripe pattern 1, the smallpox antibodies to stripe pattern 2, and the toxin antibodies to stripe pattern 3, for example. If the corresponding model pathogen is present in a sample, it is "recognized" and bound by its antibodies. At this point, free antibodies that have been tagged with a fluorescent dye are added to the sample. These also dock onto the pathogen so that it is surrounded like the filling in a sandwich; giving the technique its name, "sandwich immunoassay". Measurement of the fluorescence now gives information about the pathogen concentration. Analysis of the reflection pattern allows the "barcode" of the fluorescing nanowires to be read. If only wires with stripe pattern 1 fluoresce, for example, then the sample contains anthrax spores. One particular advantage of nanowires over other antibody supports is that the tests do not take place at a surface but instead in a suspension, which makes them run much faster and more accurately. If nickel stripes are also added to the ends of the wires, they can then be magnetically separated out during the required washing steps--a prerequisite for a portable microbiodetector.
Contact: Jeffrey B.-H. Tok
tok2@llnl.gov
925-423-1549
John Wiley & Sons, Inc.
When dangerous infectious diseases or biological weapons are suspected, fast help is required. The first step is a reliable, sensitive, and unambiguous, yet also fast and simple, identification of the pathogen; preferably, this test should be carried out on the spot, not in a laboratory. Portable miniature biodetection systems that can detect multiple pathogens simultaneously would be ideal for this task. American researchers from Lawrence Livermore National Laboratory led by Jeffrey Tok, in collaboration with groups at Stanford University, University of California at Davis, and Oxonica Inc (formerly Nanoplex Technologies Inc). have now developed a new basis for such a multiplex device: they are using silver and gold "striped" nanowires as supports for simultaneous immunological tests for various pathogens. Individual patterns of stripes act in the role of "barcodes". These "nanobarcoded" particles are manufactured by Oxonica Inc using template-assisted electrochemical deposition of metals within the tiny cylindrical pores of alumina membranes. When deposited gold and silver are alternated in a defined way, nanowires with different characteristic stripe patterns are produced. The pattern of optical reflections from each sequence of stripes can later be unambiguously recognized--just like a barcode.
Antibodies aimed at specific pathogens can be attached to these wires. For their test runs, Tok and his colleagues selected harmless model substances to stand in for anthrax spores, smallpox virus, and protein toxins such as ricin and botulinum toxin. If a simultaneous test for all of these is desired, the anthrax antibody would be attached to stripe pattern 1, the smallpox antibodies to stripe pattern 2, and the toxin antibodies to stripe pattern 3, for example. If the corresponding model pathogen is present in a sample, it is "recognized" and bound by its antibodies. At this point, free antibodies that have been tagged with a fluorescent dye are added to the sample. These also dock onto the pathogen so that it is surrounded like the filling in a sandwich; giving the technique its name, "sandwich immunoassay". Measurement of the fluorescence now gives information about the pathogen concentration. Analysis of the reflection pattern allows the "barcode" of the fluorescing nanowires to be read. If only wires with stripe pattern 1 fluoresce, for example, then the sample contains anthrax spores. One particular advantage of nanowires over other antibody supports is that the tests do not take place at a surface but instead in a suspension, which makes them run much faster and more accurately. If nickel stripes are also added to the ends of the wires, they can then be magnetically separated out during the required washing steps--a prerequisite for a portable microbiodetector.
Contact: Jeffrey B.-H. Tok
tok2@llnl.gov
925-423-1549
John Wiley & Sons, Inc.
Greenland's ice loss accelerating rapidly, gravity-measuring satellites reveal
A new analysis of data from twin satellites has revealed that the melting of Greenland's ice sheet has increased dramatically in the past few years, with much of the loss occurring primarily along one shoreline potentially affecting weather in Western Europe.
The loss of ice has been occurring about five times faster from Greenland's southeastern region in the past two years than in the previous year and a half. The dramatic changes were documented during a University of Texas at Austin study of Greenland's mass between 2002 and 2005.
The study was published today in the journal Science. Related results on the significant loss of ice from Antarctica were published in Science in March by other researchers participating in the Gravity Recovery and Climate Experiment (GRACE) mission. The GRACE mission is funded by NASA and the German Aerospace Center, and led by Aerospace Engineering Professor Byron Tapley at the university.
"Our latest GRACE findings are the most complete measurement of ice mass loss for Greenland," said Tapley, director of the university's Center for Space Research (CSR) and holder of the Clare Cockrell Williams Centennial Chair in Engineering. "The sobering thing to see is that the whole process of glacial melting is stepping up much more rapidly than before."
Antarctica is considered the largest, and Greenland the second largest, reservoir of fresh water on Earth, with the latter containing about 10 percent of the world's fresh water. Melting of ice from these two regions is expected to impact sea level and ocean circulation, and potentially the future of climates worldwide.
The Greenland study, for example, suggests that the amount of fresh water contributed from the melting of its ice sheet could add 0.56 millimeters annually to a global increase in sea levels, higher than all previously published measurements.
"These findings are consistent with the most recent independent measurements of Greenland's mass done by other techniques like satellite radar interferometry, but in this case they provide a direct measure of ice-mass changes," said Geology Professor Clark Wilson, a co-author on the latest Science article who helped analyze the estimates for Greenland. Wilson chairs the Department of Geological Sciences at the university and holds the Wallace E. Pratt Professorship in Geophysics.
Within the subpolar zone that includes Greenland, the rapid rise in meltwater along its eastern coast could add to other warming-related factors believed to be weakening the counterclockwise flow of the North Atlantic Current. For instance, the increased meltwater could change how more buoyant fresh water mixes with salt water in a branch of this flow called the Norwegian Current. This change could lower the temperatures of water, and thus wind, that travels past the west coast of Ireland and Great Britain.
That ocean temperature change would occur because the current might not move northward past Norway before returning to more southerly latitudes. Warmer, southerly waters would be stalled from moving northward if that happened, resulting in chillier winters in parts of Western Europe.
"If enough fresh water enters the Norwegian Current," Tapley said, "and you interrupt return flow, then there could be climate effects in Europe."
The twin GRACE satellites provide the most comprehensive monthly estimates of Greenland's ice-mass balance The satellites are sensitive to the gravitational pull of mass changes on Earth, which produce micrometer-scale variations in the distance (137 miles or 220 kilometers) that separates the two satellites as they fly in formation over Earth.
Lead author Jianli Chen, a CSR research scientist, developed a method to improve the effective spatial resolution of mass change estimates. The method used the known locations of major glaciers as information in estimating the sources of mass change.
"By using this special filtering procedure," Chen said, "we teased out additional details of mass changes in Greenland along its Southeastern and Northeastern shores separately."
The estimates showed that 69 percent of the ice-mass loss in recent years came from eastern Greenland. Of the 57 cubic miles (239 cubic kilometers) of water mass lost on average each year, 39 cubic miles (164 cubic kilometers) were from the eastern shoreline. More than half of that eastern loss involved ice from the glacier complex in southeast Greenland.
"This melting process may be approaching a point where it won't be centuries before Greenland's ice melts, but a much shorter time-frame," Tapley said, noting that it isn't possible to tell how much sooner this will be.
Tapley in the College of Engineering, and Wilson, whose department is part of the Jackson School of Geosciences, lead grants funded primarily by NASA to pursue research questions related to large-scale mass changes impacting Earth's features.
Contact: Becky Rische
brische@mail.utexas.edu
512-471-7272
University of Texas at Austin
The loss of ice has been occurring about five times faster from Greenland's southeastern region in the past two years than in the previous year and a half. The dramatic changes were documented during a University of Texas at Austin study of Greenland's mass between 2002 and 2005.
The study was published today in the journal Science. Related results on the significant loss of ice from Antarctica were published in Science in March by other researchers participating in the Gravity Recovery and Climate Experiment (GRACE) mission. The GRACE mission is funded by NASA and the German Aerospace Center, and led by Aerospace Engineering Professor Byron Tapley at the university.
"Our latest GRACE findings are the most complete measurement of ice mass loss for Greenland," said Tapley, director of the university's Center for Space Research (CSR) and holder of the Clare Cockrell Williams Centennial Chair in Engineering. "The sobering thing to see is that the whole process of glacial melting is stepping up much more rapidly than before."
Antarctica is considered the largest, and Greenland the second largest, reservoir of fresh water on Earth, with the latter containing about 10 percent of the world's fresh water. Melting of ice from these two regions is expected to impact sea level and ocean circulation, and potentially the future of climates worldwide.
The Greenland study, for example, suggests that the amount of fresh water contributed from the melting of its ice sheet could add 0.56 millimeters annually to a global increase in sea levels, higher than all previously published measurements.
"These findings are consistent with the most recent independent measurements of Greenland's mass done by other techniques like satellite radar interferometry, but in this case they provide a direct measure of ice-mass changes," said Geology Professor Clark Wilson, a co-author on the latest Science article who helped analyze the estimates for Greenland. Wilson chairs the Department of Geological Sciences at the university and holds the Wallace E. Pratt Professorship in Geophysics.
Within the subpolar zone that includes Greenland, the rapid rise in meltwater along its eastern coast could add to other warming-related factors believed to be weakening the counterclockwise flow of the North Atlantic Current. For instance, the increased meltwater could change how more buoyant fresh water mixes with salt water in a branch of this flow called the Norwegian Current. This change could lower the temperatures of water, and thus wind, that travels past the west coast of Ireland and Great Britain.
That ocean temperature change would occur because the current might not move northward past Norway before returning to more southerly latitudes. Warmer, southerly waters would be stalled from moving northward if that happened, resulting in chillier winters in parts of Western Europe.
"If enough fresh water enters the Norwegian Current," Tapley said, "and you interrupt return flow, then there could be climate effects in Europe."
The twin GRACE satellites provide the most comprehensive monthly estimates of Greenland's ice-mass balance The satellites are sensitive to the gravitational pull of mass changes on Earth, which produce micrometer-scale variations in the distance (137 miles or 220 kilometers) that separates the two satellites as they fly in formation over Earth.
Lead author Jianli Chen, a CSR research scientist, developed a method to improve the effective spatial resolution of mass change estimates. The method used the known locations of major glaciers as information in estimating the sources of mass change.
"By using this special filtering procedure," Chen said, "we teased out additional details of mass changes in Greenland along its Southeastern and Northeastern shores separately."
The estimates showed that 69 percent of the ice-mass loss in recent years came from eastern Greenland. Of the 57 cubic miles (239 cubic kilometers) of water mass lost on average each year, 39 cubic miles (164 cubic kilometers) were from the eastern shoreline. More than half of that eastern loss involved ice from the glacier complex in southeast Greenland.
"This melting process may be approaching a point where it won't be centuries before Greenland's ice melts, but a much shorter time-frame," Tapley said, noting that it isn't possible to tell how much sooner this will be.
Tapley in the College of Engineering, and Wilson, whose department is part of the Jackson School of Geosciences, lead grants funded primarily by NASA to pursue research questions related to large-scale mass changes impacting Earth's features.
Contact: Becky Rische
brische@mail.utexas.edu
512-471-7272
University of Texas at Austin
Today's babies are fatter babies
Twenty-two-year study shows that young kids are now more likely to be overweight
Boston -- By examining more than 120,000 children under age 6 in Massachusetts over 22 years, a newly published study shows that young children--especially infants--are now more likely to be overweight. This study was based at the Department of Ambulatory Care and Prevention of Harvard Medical School and Harvard Pilgrim Health Care and appears in the July issue of Obesity.
"The obesity epidemic has spared no age group, even our youngest children," says Matthew Gillman, MD, senior author of the study and associate professor in the Department of Ambulatory Care and Prevention (of Harvard Medical School and Harvard Pilgrim Health Care).
Over the course of the study, the prevalence of overweight children increased from 6.3 percent to 10 percent, a 59 percent jump (based on weight and height measures documented in medical records). The proportion of children at risk of becoming overweight grew from 11.1 percent to 14.4 percent overall, a 30 percent jump.
Infants from birth to six months of age, an age group seldom studied before, had particularly surprising results. Of all the age groups studied, these infants had the greatest jump in risk of becoming overweight, at 59 percent, and the number of overweight infants increased by 74 percent. "This information is important to public health because previous studies show that accelerated weight gain in the first few months after birth is associated with obesity later in life," says Gillman.
According to the Centers for Disease Control and Prevention's national reference data, children with a weight-for-height index between the national 85th and 95th percentiles for age and gender are classified as at risk for becoming overweight, and those with a weight-for-height index greater than the 95th percentile are classified as overweight. Access the CDC's growth charts at http://www.cdc.gov/growthcharts/.
"In addition to demonstrating that we are seeing more heavy infants today than we did 20 years ago, this study illustrates the usefulness of routinely collected information from doctors' offices to address a key public health issue," says Juhee Kim, PhD, first author of the study. Kim performed this research at DACP while she was a research fellow in the Public Health Nutrition Program at the Harvard School of Public Health.
Gillman and colleagues collected data from well-child visits among more than 120,000 children younger than 6 years old at 14 Harvard Vanguard Medical Associates practices in eastern Massachusetts from 1980 through 2001. All of the children were enrolled in an HMO, which, throughout the study, used a completely electronic medical record system that contained demographic and growth data for the children.
"These results show that efforts to prevent obesity must start at the earliest stages of human development, even before birth," says Gillman. "These efforts should include avoiding smoking and excessive weight gain during pregnancy, preventing gestational diabetes, and promoting breastfeeding, all of which researchers have shown to be associated with reductions in childhood overweight."
Contact: Leah Gourley
public_affairs@hms.harvard.edu
617-432-0442
Harvard Medical School
Boston -- By examining more than 120,000 children under age 6 in Massachusetts over 22 years, a newly published study shows that young children--especially infants--are now more likely to be overweight. This study was based at the Department of Ambulatory Care and Prevention of Harvard Medical School and Harvard Pilgrim Health Care and appears in the July issue of Obesity.
"The obesity epidemic has spared no age group, even our youngest children," says Matthew Gillman, MD, senior author of the study and associate professor in the Department of Ambulatory Care and Prevention (of Harvard Medical School and Harvard Pilgrim Health Care).
Over the course of the study, the prevalence of overweight children increased from 6.3 percent to 10 percent, a 59 percent jump (based on weight and height measures documented in medical records). The proportion of children at risk of becoming overweight grew from 11.1 percent to 14.4 percent overall, a 30 percent jump.
Infants from birth to six months of age, an age group seldom studied before, had particularly surprising results. Of all the age groups studied, these infants had the greatest jump in risk of becoming overweight, at 59 percent, and the number of overweight infants increased by 74 percent. "This information is important to public health because previous studies show that accelerated weight gain in the first few months after birth is associated with obesity later in life," says Gillman.
According to the Centers for Disease Control and Prevention's national reference data, children with a weight-for-height index between the national 85th and 95th percentiles for age and gender are classified as at risk for becoming overweight, and those with a weight-for-height index greater than the 95th percentile are classified as overweight. Access the CDC's growth charts at http://www.cdc.gov/growthcharts/.
"In addition to demonstrating that we are seeing more heavy infants today than we did 20 years ago, this study illustrates the usefulness of routinely collected information from doctors' offices to address a key public health issue," says Juhee Kim, PhD, first author of the study. Kim performed this research at DACP while she was a research fellow in the Public Health Nutrition Program at the Harvard School of Public Health.
Gillman and colleagues collected data from well-child visits among more than 120,000 children younger than 6 years old at 14 Harvard Vanguard Medical Associates practices in eastern Massachusetts from 1980 through 2001. All of the children were enrolled in an HMO, which, throughout the study, used a completely electronic medical record system that contained demographic and growth data for the children.
"These results show that efforts to prevent obesity must start at the earliest stages of human development, even before birth," says Gillman. "These efforts should include avoiding smoking and excessive weight gain during pregnancy, preventing gestational diabetes, and promoting breastfeeding, all of which researchers have shown to be associated with reductions in childhood overweight."
Contact: Leah Gourley
public_affairs@hms.harvard.edu
617-432-0442
Harvard Medical School
Friday, September 22, 2006
First-ever genomic test predicts which lung cancer patients need chemotherapy to live
DURHAM, N.C. –Duke University Medical Center scientists have developed the first-ever genomic test to predict which patients with early-stage lung cancer will need chemotherapy to live and which patients can avoid the toxic regimen of drugs.
The test has the potential to save thousands of lives each year by recommending chemotherapy for patients who are currently advised against it, said the test's developers at Duke's Institute for Genome Sciences & Policy.
The test's promising results have initiated a landmark multi-center clinical trial, to be led by Duke investigators next year. Patients with early-stage non-small cell lung cancer, the most common and fatal form of cancer, will receive the genomic test and its results will determine their treatment.
The new test, called the Lung Metagene Predictor, scans thousands of genes to identify patterns of gene activity in individual tumors that indicate a patient is likely to suffer a recurrence of disease. Recurrent tumors are typically fatal, so identifying at-risk patients is critical to properly treating them, said the Duke researchers.
"Using the unique genomic signatures from each tumor, our new test predicted with up to 90 percent accuracy which early-stage lung cancer patients would suffer a recurrence of their cancer and which patients would not," said Anil Potti, M.D., an assistant professor of medicine and lead author of the study. "We now have a tool that can be used to move these high-risk patients from the 'no chemotherapy' group into the aggressive treatment group."
The researchers will publish their findings in the Aug. 10, 2006, issue of the New England Journal of Medicine. The research was funded by the National Institutes of Health.
The genomic test can theoretically apply to any cancer, but the Duke team focused its effort on lung cancer because the survival rate is just 15 percent. Lung cancer now kills more Americans each year than breast, prostate and colorectal cancers combined. But toxic chemotherapy drugs are prescribed only to patients with relatively large and aggressive tumors.
Early-stage patients – those with small, stationary tumors – are considered at low risk of recurrence. Hence, they only receive surgery but not chemotherapy. The dilemma, said Potti, is that a third or more of early-stage patients who appear to be at low risk will experience a recurrent tumor.
"Until now, there simply has been no way to identify the 30 percent to 40 percent of early-stage lung cancer patients who would experience a recurrence," Potti said. "Now, with our test, we can say with confidence that we can identify this group of patients so they can be treated accordingly."
The upcoming trial is the first to use a genomic test to select treatment options for individual lung cancer patients, said David Harpole, M.D., a professor of thoracic surgery at Duke and principal investigator of the upcoming clinical trial. The trial, to begin within six months, will enroll more than 1,000 patients at multiple centers in the United States and Canada.
"If we can use the test to increase patient survival by even 5 percent, we would save 10,000 lives a year," Harpole said.
The Duke researchers developed the test by analyzing the activity of genes from early-stage lung cancer patients whose disease outcomes were known. The Duke scientists then validated the genomic test in 129 patients by comparing the test's predictions with the patient's actual outcomes. The test predicted their risk of recurrence with 90 percent accuracy, the study showed.
If proven to be effective in the clinical trial, the test will replace the current method of assessing risk, which is imprecise and provides only a broad estimate of a patient's risk, said Joseph Nevins, Ph.D., a professor of molecular genetics at Duke and senior author of the study being reported.
Physicians now assign each patient to a clinical "stage" based on the size of the patient's tumor, whether it has invaded lymph nodes and whether it has spread to other organs. They use this staging method to prescribe the best treatment options. But staging parameters are general, at best, and do not accurately define who should receive chemotherapy, Nevins said.
"Instead of placing all patients with small tumors in the same early-stage category, as physicians currently would do, we can now assess their risk based on the tumor's genomic profile," Nevins said. "The current system of 'staging' lung cancer tumors will eventually become obsolete."
To employ the test, physicians take a sample of the tumor as it is removed during surgery. They extract its "messenger RNA," which represents the activity of thousands of genes in the tumor. Messenger RNA translates a gene's DNA code into proteins that run the cell's activities. Hence, it is a barometer of a gene's activity level inside the cell.
Scientists label the messenger RNA with fluorescent tags. The fluorescent RNA is then placed on a tiny glass slide, called a gene chip. There, it binds to its complementary DNA sequence on the gene chip.
When scanned with special light, the fluorescent RNA emits a telltale luminescence that demonstrates how much RNA is present on the chip – and thus which genes are most active in a given tumor. The physicians then use a rigorous statistical analysis to assess the relative risk of large grouping of genes, called metagenes, which have similar characteristics.
The test generates a risk "number" for each patient. If their risk exceeds 50 percent, the patient is advised to get chemotherapy.
"This new genomic test is a clear example of personalized medicine, where we use the unique molecular characteristics of each patient's tumor to guide treatment decisions," said Geoffrey Ginsburg, M.D., Ph.D., a professor of medicine and co-author of the study.
Eventually, physicians will use genomic tests not only to predict patient outcomes, but also to select the individual drugs that will best match a tumor's molecular makeup, Ginsburg said.
Contact: Marla Vacek Broadfoot
marla.broadfoot@duke.edu
919-660-1306
Duke University Medical Center
The test has the potential to save thousands of lives each year by recommending chemotherapy for patients who are currently advised against it, said the test's developers at Duke's Institute for Genome Sciences & Policy.
The test's promising results have initiated a landmark multi-center clinical trial, to be led by Duke investigators next year. Patients with early-stage non-small cell lung cancer, the most common and fatal form of cancer, will receive the genomic test and its results will determine their treatment.
The new test, called the Lung Metagene Predictor, scans thousands of genes to identify patterns of gene activity in individual tumors that indicate a patient is likely to suffer a recurrence of disease. Recurrent tumors are typically fatal, so identifying at-risk patients is critical to properly treating them, said the Duke researchers.
"Using the unique genomic signatures from each tumor, our new test predicted with up to 90 percent accuracy which early-stage lung cancer patients would suffer a recurrence of their cancer and which patients would not," said Anil Potti, M.D., an assistant professor of medicine and lead author of the study. "We now have a tool that can be used to move these high-risk patients from the 'no chemotherapy' group into the aggressive treatment group."
The researchers will publish their findings in the Aug. 10, 2006, issue of the New England Journal of Medicine. The research was funded by the National Institutes of Health.
The genomic test can theoretically apply to any cancer, but the Duke team focused its effort on lung cancer because the survival rate is just 15 percent. Lung cancer now kills more Americans each year than breast, prostate and colorectal cancers combined. But toxic chemotherapy drugs are prescribed only to patients with relatively large and aggressive tumors.
Early-stage patients – those with small, stationary tumors – are considered at low risk of recurrence. Hence, they only receive surgery but not chemotherapy. The dilemma, said Potti, is that a third or more of early-stage patients who appear to be at low risk will experience a recurrent tumor.
"Until now, there simply has been no way to identify the 30 percent to 40 percent of early-stage lung cancer patients who would experience a recurrence," Potti said. "Now, with our test, we can say with confidence that we can identify this group of patients so they can be treated accordingly."
The upcoming trial is the first to use a genomic test to select treatment options for individual lung cancer patients, said David Harpole, M.D., a professor of thoracic surgery at Duke and principal investigator of the upcoming clinical trial. The trial, to begin within six months, will enroll more than 1,000 patients at multiple centers in the United States and Canada.
"If we can use the test to increase patient survival by even 5 percent, we would save 10,000 lives a year," Harpole said.
The Duke researchers developed the test by analyzing the activity of genes from early-stage lung cancer patients whose disease outcomes were known. The Duke scientists then validated the genomic test in 129 patients by comparing the test's predictions with the patient's actual outcomes. The test predicted their risk of recurrence with 90 percent accuracy, the study showed.
If proven to be effective in the clinical trial, the test will replace the current method of assessing risk, which is imprecise and provides only a broad estimate of a patient's risk, said Joseph Nevins, Ph.D., a professor of molecular genetics at Duke and senior author of the study being reported.
Physicians now assign each patient to a clinical "stage" based on the size of the patient's tumor, whether it has invaded lymph nodes and whether it has spread to other organs. They use this staging method to prescribe the best treatment options. But staging parameters are general, at best, and do not accurately define who should receive chemotherapy, Nevins said.
"Instead of placing all patients with small tumors in the same early-stage category, as physicians currently would do, we can now assess their risk based on the tumor's genomic profile," Nevins said. "The current system of 'staging' lung cancer tumors will eventually become obsolete."
To employ the test, physicians take a sample of the tumor as it is removed during surgery. They extract its "messenger RNA," which represents the activity of thousands of genes in the tumor. Messenger RNA translates a gene's DNA code into proteins that run the cell's activities. Hence, it is a barometer of a gene's activity level inside the cell.
Scientists label the messenger RNA with fluorescent tags. The fluorescent RNA is then placed on a tiny glass slide, called a gene chip. There, it binds to its complementary DNA sequence on the gene chip.
When scanned with special light, the fluorescent RNA emits a telltale luminescence that demonstrates how much RNA is present on the chip – and thus which genes are most active in a given tumor. The physicians then use a rigorous statistical analysis to assess the relative risk of large grouping of genes, called metagenes, which have similar characteristics.
The test generates a risk "number" for each patient. If their risk exceeds 50 percent, the patient is advised to get chemotherapy.
"This new genomic test is a clear example of personalized medicine, where we use the unique molecular characteristics of each patient's tumor to guide treatment decisions," said Geoffrey Ginsburg, M.D., Ph.D., a professor of medicine and co-author of the study.
Eventually, physicians will use genomic tests not only to predict patient outcomes, but also to select the individual drugs that will best match a tumor's molecular makeup, Ginsburg said.
Contact: Marla Vacek Broadfoot
marla.broadfoot@duke.edu
919-660-1306
Duke University Medical Center
New method of growing carbon nanotubes to revolutionise electronics
A new method of growing carbon nanotubes is predicted to revolutionise the implementation of nanotechnology and the future of electronics. Researchers at the University of Cambridge have successfully grown nanotubes at a temperature which permits their full integration into present complementary ) technology (350 ºC).
Carbon nanotubes are the driving force for current advances in nanotechnology; they have excellent mechanical and electronic properties, the latter making them extremely attractive for new-generation electronics.
Increasing efficiency through smaller components is the key towards miniaturisation of technology. The use of carbon nanotubes could find successful use from sophisticated, niche applications to everyday electronics (mobile phones, computers).
Thus far the growth of nanotubes has been carried out at very high temperatures, and growth below 500 °C was believed impossible. This made the direct implementation of nanotubes into electronic devices unthinkable. Trying to integrate nanotubes above 400–450 °C would in fact damage the inter-metal dielectrics commonly employed in CMOS device fabrication.
A group of researchers at the Department of Engineering at the University of Cambridge, led by Mirco Cantoro, Stephan Hofmann, Andrea Ferrari and John Robertson, in collaboration with colleagues at the Cambridge Hitachi Laboratory and the Department of Materials Science, University of Cambridge, succeeded in growing single-wall carbon nanotubes at temperatures as low as 350 ºC.
These nanotubes, grown by thermal Chemical Vapour Deposition (a chemical process often used in the semiconductor industry), are promising candidates for integration into existing nanoelectronic devices.
This result also sheds new light on the possible mechanisms that occur during carbon nanotube growth. Previously, the assumption that the catalyst has to be liquid often dominated carbon nanotube growth model considerations, but at these lower temperatures evidence has been found of a solid catalyst. These findings extend to the catalytic growth of other nanostructures in general.
Carbon nanotubes are the driving force for current advances in nanotechnology; they have excellent mechanical and electronic properties, the latter making them extremely attractive for new-generation electronics.
Increasing efficiency through smaller components is the key towards miniaturisation of technology. The use of carbon nanotubes could find successful use from sophisticated, niche applications to everyday electronics (mobile phones, computers).
Thus far the growth of nanotubes has been carried out at very high temperatures, and growth below 500 °C was believed impossible. This made the direct implementation of nanotubes into electronic devices unthinkable. Trying to integrate nanotubes above 400–450 °C would in fact damage the inter-metal dielectrics commonly employed in CMOS device fabrication.
A group of researchers at the Department of Engineering at the University of Cambridge, led by Mirco Cantoro, Stephan Hofmann, Andrea Ferrari and John Robertson, in collaboration with colleagues at the Cambridge Hitachi Laboratory and the Department of Materials Science, University of Cambridge, succeeded in growing single-wall carbon nanotubes at temperatures as low as 350 ºC.
These nanotubes, grown by thermal Chemical Vapour Deposition (a chemical process often used in the semiconductor industry), are promising candidates for integration into existing nanoelectronic devices.
This result also sheds new light on the possible mechanisms that occur during carbon nanotube growth. Previously, the assumption that the catalyst has to be liquid often dominated carbon nanotube growth model considerations, but at these lower temperatures evidence has been found of a solid catalyst. These findings extend to the catalytic growth of other nanostructures in general.
Subscribe to:
Posts (Atom)