A paper by researchers at the National Institute of Standards and Technology (NIST) may breathe new life into the use of a powerful - but tricky - diagnostic technique for cell biology. The paper,* appearing this week in the Biophysical Journal, demonstrates that with improved hardware and better signal processing, a powerful form of molecular vibration spectroscopy can quickly deliver detailed molecular maps of the contents of cells without damaging them. Earlier studies have suggested that to be useful, the technique would need power levels too high for cells.
The technique, "B-CARS,"** is one of several variations on Raman spectroscopy, which measures the frequencies associated with different modes of vibration of atoms and their bonds in a molecule. The exact mix of these frequencies is an extremely discriminating "fingerprint" for any particular molecule, so Raman spectroscopy has been used as a chemical microscope, able to detail the structure of complex objects by mapping the chemical composition at each point in a three-dimensional space.
In the biosciences, according to NIST chemist Marcus Cicerone, Raman spectroscopy has been used to detect microscopic cellular components such as mitochondria, detect how stem cells differentiate into new forms and distinguish between subtly different cell and tissue types. It can, for example, detect minor differences between various precancerous and cancerous cells, potentially providing valuable medical diagnostic information. Even better, it does this without the need to add fluorescent dyes or other chemical tags to identify specific proteins.
The catch, says Cicerone, is speed. The usual method, spontaneous Raman scattering takes a long time to gather enough data to generate a single spectrum - as much as seven minutes for fine detail - and that's for each point in the image. "Seven minutes or even five seconds per spectrum is not feasible when we need a million spectra for an image," he observes. CARS, which uses a pair of lasers to pump up the vibrational states and increase signal, is part of the answer. The current breakthroughs for a broadband CARS instrument developed at NIST since 2004, says Cicerone, gets the same information in 50 milliseconds per pixel.
The new catch is power. Recent papers have argued that to get the necessary data, the lasers used in CARS must run at power levels above the damage threshold for living cells, making the technique nearly useless for clinical purposes. Not quite, according to the NIST team. Their paper describes a combination of improved hardware to gather spectra over a very broad range of wavelengths, and a clever mathematical technique that effectively amplifies the useable signal by examining a portion of signal normally ignored as background interference. The result, says Cicerone, pushes their minimum power level below the damage threshold while retaining the speed of CARS. "We have all the information that you have in a Raman spectrum but we get it 5 to 100 times faster," he says, adding that some obvious modifications should push that higher, opening the door to more widespread use of vibrational spectroscopy in both biology and clinical diagnosis.
Notes:
* S.H. Parekh, Y.J. Lee, K.A. Aamer and M.T. Cicerone. Label-free cellular imaging by broadband coherent anti-Stokes Raman scattering microscopy. Biophysical Journal. V. 99, Oct. 13, 2010.
** For "broadband coherent anti-Stokes Raman scattering"
Source:
Michael Baum
National Institute of Standards and Technology (NIST)
вторник, 30 августа 2011 г.
суббота, 27 августа 2011 г.
Preventing Cancer Without Killing Cells
Inducing senescence in aged cells may be sufficient to guard against spontaneous cancer development, according to a paper published online this week in EMBO reports. It was previously unknown whether cellular senescence or programmed cell death apoptosis was the more important safeguard mechanism for suppressing tumours arising from dysfunctional telomeres.
Aged cells have abnormal chromosomes with dysfunctional telomeres shorter ends that can promote tumorigenesis in the absence of the tumour suppressor p53, and may be related to the higher incidence of cancer in older individuals. However, in the presence of p53, dysfunctional telomeres can induce a permanent arrest of cell growth, known as senescence. Sandy Chang and colleagues studied mutant mice with dysfunctional telomeres and copies of the p53 gene that cannot initiate p53-dependent apoptosis but can execute p53-mediated senescence.
The authors found that activating the senescence pathway was sufficient to suppress spontaneous tumorigenesis. Their findings suggest that, by halting cellular proliferation, p53-mediated senescence may act as an important tumour suppressor mechanism in aged cells.
EUROPEAN MOLECULAR BIOLOGY ORGANIZATION (EMBO)
Postfach 1022.40
D-69012 Heidelberg
embo
Aged cells have abnormal chromosomes with dysfunctional telomeres shorter ends that can promote tumorigenesis in the absence of the tumour suppressor p53, and may be related to the higher incidence of cancer in older individuals. However, in the presence of p53, dysfunctional telomeres can induce a permanent arrest of cell growth, known as senescence. Sandy Chang and colleagues studied mutant mice with dysfunctional telomeres and copies of the p53 gene that cannot initiate p53-dependent apoptosis but can execute p53-mediated senescence.
The authors found that activating the senescence pathway was sufficient to suppress spontaneous tumorigenesis. Their findings suggest that, by halting cellular proliferation, p53-mediated senescence may act as an important tumour suppressor mechanism in aged cells.
EUROPEAN MOLECULAR BIOLOGY ORGANIZATION (EMBO)
Postfach 1022.40
D-69012 Heidelberg
embo
среда, 24 августа 2011 г.
Obesity Battle Aided By Red Wine's Resveratrol
Resveratrol, a compound present in grapes and red wine, reduces the number of fat cells and may one day be used to treat or prevent obesity, according to a new study. The results were presented at The Endocrine Society's 90th Annual Meeting in San Francisco.
Past research found that resveratrol protected laboratory mice that were fed a high-calorie diet from the health problems of obesity, by mimicking the effects of calorie restriction. Researchers at the University of Ulm in Germany wanted to know if resveratrol could mimic the effects of calorie restriction in human fat cells by changing their size or function. The German team used a strain of human fat cell precursors, called preadipocytes. In the body, these cells develop into mature fat cells, according to the study's lead author, Pamela Fischer-Posovszky, PhD, a pediatric endocrinology research fellow in the university's Diabetes and Obesity Unit.
In the cell-based study, they found that resveratrol inhibited the pre-fat cells from increasing and prevented them from converting into mature fat cells. Also, resveratrol hindered fat storage. Most interesting, according to Fischer-Posovszky, was that resveratrol reduced production of certain cytokines (interleukins 6 and 8), substances that may be linked to the development of obesity-related disorders, such as diabetes and clogged coronary arteries. Also, resveratrol stimulated formation of a protein known to decrease the risk of heart attack. Obesity decreases this substance, called adiponectin.
The new finding is consistent with the theory that the resveratrol in red wine explains the French paradox, the observation that French people eat a relatively high-fat diet but have a low death rate from heart disease.
"Resveratrol has anti-obesity properties by exerting its effects directly on the fat cells," Fischer-Posovszky said. "Thus, resveratrol might help to prevent development of obesity or might be suited to treating obesity."
Fischer-Posovszky cautioned that, while the health benefits of resveratrol seem promising, there is not sufficient knowledge about the effects of long-term treatment. One small study found that a single dose of up to 5 grams of resveratrol (much higher than the amount in a bottle of red wine) caused no serious ill effects in healthy volunteers, she pointed out. However, she said another study theorized that resveratrol may stimulate the growth of human breast cancer cells, possibly because resveratrol's chemical structure is similar to a phytoestrogen, an estrogen-like substance found in some plants.
This study was partly funded by the German Research Association (Deutsche Forschungsgemeinschaft) and the Ministry of Science, Research and Arts (Ministerium fuer Wissenschaft, Forschung und Kunst), Baden-Wuerttemberg.
Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones, and the clinical practice of endocrinology. Today, The Endocrine Society's membership consists of over 14,000 scientists, physicians, educators, nurses and students in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society, and the field of endocrinology, visit our web site at endo-society/.
Source: Aaron Lohr
The Endocrine Society
Past research found that resveratrol protected laboratory mice that were fed a high-calorie diet from the health problems of obesity, by mimicking the effects of calorie restriction. Researchers at the University of Ulm in Germany wanted to know if resveratrol could mimic the effects of calorie restriction in human fat cells by changing their size or function. The German team used a strain of human fat cell precursors, called preadipocytes. In the body, these cells develop into mature fat cells, according to the study's lead author, Pamela Fischer-Posovszky, PhD, a pediatric endocrinology research fellow in the university's Diabetes and Obesity Unit.
In the cell-based study, they found that resveratrol inhibited the pre-fat cells from increasing and prevented them from converting into mature fat cells. Also, resveratrol hindered fat storage. Most interesting, according to Fischer-Posovszky, was that resveratrol reduced production of certain cytokines (interleukins 6 and 8), substances that may be linked to the development of obesity-related disorders, such as diabetes and clogged coronary arteries. Also, resveratrol stimulated formation of a protein known to decrease the risk of heart attack. Obesity decreases this substance, called adiponectin.
The new finding is consistent with the theory that the resveratrol in red wine explains the French paradox, the observation that French people eat a relatively high-fat diet but have a low death rate from heart disease.
"Resveratrol has anti-obesity properties by exerting its effects directly on the fat cells," Fischer-Posovszky said. "Thus, resveratrol might help to prevent development of obesity or might be suited to treating obesity."
Fischer-Posovszky cautioned that, while the health benefits of resveratrol seem promising, there is not sufficient knowledge about the effects of long-term treatment. One small study found that a single dose of up to 5 grams of resveratrol (much higher than the amount in a bottle of red wine) caused no serious ill effects in healthy volunteers, she pointed out. However, she said another study theorized that resveratrol may stimulate the growth of human breast cancer cells, possibly because resveratrol's chemical structure is similar to a phytoestrogen, an estrogen-like substance found in some plants.
This study was partly funded by the German Research Association (Deutsche Forschungsgemeinschaft) and the Ministry of Science, Research and Arts (Ministerium fuer Wissenschaft, Forschung und Kunst), Baden-Wuerttemberg.
Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones, and the clinical practice of endocrinology. Today, The Endocrine Society's membership consists of over 14,000 scientists, physicians, educators, nurses and students in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society, and the field of endocrinology, visit our web site at endo-society/.
Source: Aaron Lohr
The Endocrine Society
воскресенье, 21 августа 2011 г.
Transgenic Mouse Models In Drug Metabolism And Transport: Free AAPS Webinar
The second part of a two-session series to discuss issues from basic research and drug development perspectives
WHO:
The American Association of Pharmaceutical Scientists (AAPS) is a professional, scientific society of approximately 12,000 members employed in industry, academia, government and other research institutes worldwide. Founded in 1986, AAPS provides a dynamic international forum for the exchange of knowledge among scientists to enhance their contributions to public health. AAPS offers timely scientific programs, on-going education, information resources, opportunities for networking, and professional development.
WHAT:
AAPS is pleased to present the complimentary eLearning Webinar on Transgenic Mouse Models in Drug Metabolism and Transport (Session II). This module is organized by the AAPS Pharmacokinetics, Pharmacodynamics and Drug Metabolism Section. This Webinar will be conducted by Xinxin Ding, Ph.D.
WHY:
The purpose of this free Webinar is to educate participants on how animal models allow direct examination of the role that a specific metabolizing enzyme or transporter plays in the disposition, clearance, efficacy, and toxicity of a particular drug or xenobiotic in a whole body system. Participants will gain understanding of the powerful insight these models provide into potential clinical outcomes associated with specific new therapeutics.
WHEN:
October 27, 2009
10:00 AM to 11:30 AM EDT
HOW:
For additional information about the workshop, and to register, visit aapspharmaceutica/webinars/transgenicmodels2.
Session I of this Webinar is archived at mediaserver.aapspharmaceutica/meetings/webinars/archives.pdf.
Source:
Joseph Catapano
American Association of Pharmaceutical Scientists
WHO:
The American Association of Pharmaceutical Scientists (AAPS) is a professional, scientific society of approximately 12,000 members employed in industry, academia, government and other research institutes worldwide. Founded in 1986, AAPS provides a dynamic international forum for the exchange of knowledge among scientists to enhance their contributions to public health. AAPS offers timely scientific programs, on-going education, information resources, opportunities for networking, and professional development.
WHAT:
AAPS is pleased to present the complimentary eLearning Webinar on Transgenic Mouse Models in Drug Metabolism and Transport (Session II). This module is organized by the AAPS Pharmacokinetics, Pharmacodynamics and Drug Metabolism Section. This Webinar will be conducted by Xinxin Ding, Ph.D.
WHY:
The purpose of this free Webinar is to educate participants on how animal models allow direct examination of the role that a specific metabolizing enzyme or transporter plays in the disposition, clearance, efficacy, and toxicity of a particular drug or xenobiotic in a whole body system. Participants will gain understanding of the powerful insight these models provide into potential clinical outcomes associated with specific new therapeutics.
WHEN:
October 27, 2009
10:00 AM to 11:30 AM EDT
HOW:
For additional information about the workshop, and to register, visit aapspharmaceutica/webinars/transgenicmodels2.
Session I of this Webinar is archived at mediaserver.aapspharmaceutica/meetings/webinars/archives.pdf.
Source:
Joseph Catapano
American Association of Pharmaceutical Scientists
четверг, 18 августа 2011 г.
Cooked Ham With A 39 Day Shelf Life, UK
Cooked ham could soon be given a 39 day shelf life, according to scientists
speaking today Tuesday 4 September 2007 at the Society for General
Microbiology's 161st Meeting at the University of Edinburgh, UK, which runs from 3-6
September 2007.
Traditional cooked ham has a maximum shelf life of three to four weeks (21-28
days), including the time from processing to shoppers buying the sliced meat in a
supermarket. Currently cooked ham has 55% of the UK cooked meat market, and to
maintain and expand this market processors are looking at new technologies to
extend shelf life and open up new European markets for pork products.
"Many dairy products such as cheeses and yoghurts and some fermented meat
products already use lactic acid producing bacteria to protect and preserve their
products, and we know these are acceptable to consumers in terms of taste", says
Roisin Lagan from the College of Agriculture, Food & Rural Enterprise in
Cookstown, County Tyrone, Northern Ireland. "We investigated the possibility of
extending the shelf life of cooked and sliced ham by treating it with a protective
culture of Lactobacillus sakei, a common lactic acid producing bacterium".
When the commercially cured and then Lactobacillus treated meat was tasted by an
untrained panel of consumers it was rated as tastier, with a better texture and
overall more acceptability than the same conventionally treated ham. Chemical
studies showed that the bacteria treated ham was drier and slightly more acidic than
the conventionally preserved version of the meat.
The food scientists then looked at the shelf life of the new product and found that
the lactic acid bacteria culture helped to prevent other types of bacteria from
growing on the treated ham, protecting it from possible contamination by food
poisoning bacteria or ones which would taint it by destroying its flavour and texture.
"This means that we have found a reliable and cost effective way of developing a
tasty ham product with a maximum shelf life of 39 days when stored at 4°C" says
Roisin Lagan. "This in turn will allow processors to have longer production runs
leading to less wastage, thus reducing the environmental impact of storing and
processing food waste. The increased shelf life will allow UK companies to compete
more effectively on a global scale. Consumers will be assured a reliable, safe
cooked ham product".
Dr Lagan is presenting the poster 'Shelf life extension of cooked ham using a bioprotective
culture' at 1030 on Tuesday 04 September 2007 in the Plenary session of the 161st
Meeting of the Society for General Microbiology at the University of Edinburgh, 03 - 06
September 2007.
Full programme details of this meeting can be found on the Society's website here. Hard copies are available
on request from the SGM.
The Society for General Microbiology is the largest microbiology society in Europe, and
has over 5,500 members worldwide. The Society provides a common meeting ground for
scientists working in research and in fields with applications in microbiology including
medicine, veterinary medicine, pharmaceuticals, industry, agriculture, food, the
environment and education.
The SGM represents the science and profession of microbiology to government, the media
and the general public; supporting microbiology education at all levels; and encouraging
careers in microbiology.
sgm.ac.uk
speaking today Tuesday 4 September 2007 at the Society for General
Microbiology's 161st Meeting at the University of Edinburgh, UK, which runs from 3-6
September 2007.
Traditional cooked ham has a maximum shelf life of three to four weeks (21-28
days), including the time from processing to shoppers buying the sliced meat in a
supermarket. Currently cooked ham has 55% of the UK cooked meat market, and to
maintain and expand this market processors are looking at new technologies to
extend shelf life and open up new European markets for pork products.
"Many dairy products such as cheeses and yoghurts and some fermented meat
products already use lactic acid producing bacteria to protect and preserve their
products, and we know these are acceptable to consumers in terms of taste", says
Roisin Lagan from the College of Agriculture, Food & Rural Enterprise in
Cookstown, County Tyrone, Northern Ireland. "We investigated the possibility of
extending the shelf life of cooked and sliced ham by treating it with a protective
culture of Lactobacillus sakei, a common lactic acid producing bacterium".
When the commercially cured and then Lactobacillus treated meat was tasted by an
untrained panel of consumers it was rated as tastier, with a better texture and
overall more acceptability than the same conventionally treated ham. Chemical
studies showed that the bacteria treated ham was drier and slightly more acidic than
the conventionally preserved version of the meat.
The food scientists then looked at the shelf life of the new product and found that
the lactic acid bacteria culture helped to prevent other types of bacteria from
growing on the treated ham, protecting it from possible contamination by food
poisoning bacteria or ones which would taint it by destroying its flavour and texture.
"This means that we have found a reliable and cost effective way of developing a
tasty ham product with a maximum shelf life of 39 days when stored at 4°C" says
Roisin Lagan. "This in turn will allow processors to have longer production runs
leading to less wastage, thus reducing the environmental impact of storing and
processing food waste. The increased shelf life will allow UK companies to compete
more effectively on a global scale. Consumers will be assured a reliable, safe
cooked ham product".
Dr Lagan is presenting the poster 'Shelf life extension of cooked ham using a bioprotective
culture' at 1030 on Tuesday 04 September 2007 in the Plenary session of the 161st
Meeting of the Society for General Microbiology at the University of Edinburgh, 03 - 06
September 2007.
Full programme details of this meeting can be found on the Society's website here. Hard copies are available
on request from the SGM.
The Society for General Microbiology is the largest microbiology society in Europe, and
has over 5,500 members worldwide. The Society provides a common meeting ground for
scientists working in research and in fields with applications in microbiology including
medicine, veterinary medicine, pharmaceuticals, industry, agriculture, food, the
environment and education.
The SGM represents the science and profession of microbiology to government, the media
and the general public; supporting microbiology education at all levels; and encouraging
careers in microbiology.
sgm.ac.uk
понедельник, 15 августа 2011 г.
Common Field Mice Confirm Genetic Change Happens Fast
While looks can be deceiving, heredity is revealing, and two scientists who've studied the genetic makeup of a common field mouse report that what's most revealing to them is how fast both genes and morphology can change.
Oliver Pergams, visiting research assistant professor of biological sciences at the University of Illinois at Chicago, and Robert Lacy, population geneticist and conservation biologist at the Chicago Zoological Society, compared the genetic makeup of 115 white-footed mice in the Volo Bog State Natural Area northwest of Chicago using mitochondrial DNA taken from collection samples as old as 150 years and mice collected in recent years.
They found a new type of mouse replaced the old type in Volo Bog between 1976 and 2001.
"The new mice were genetically very different," says Pergams. Structural changes were readily apparent. "Looking at size and shape, the new mice were much bigger and a little flatter."
Pergams and Lacy report the findings in Molecular Ecology, Volume 17, now online, and in print in late December.
Pergams and UIC biological sciences professor Mary Ashley reported in 2001 on similar morphological changes in size and shape over the past century of two widely disparate habitats and species -- deer mice on three different California Channel Islands, and black rats from two Galapagos Islands. While Pergams found these coincidental changes surprising, he said it is too soon to say if this is somehow related to world climate change.
Pergams said the Volo Bog change is best explained by the old mice being replaced by new mice migrating from distinct neighboring populations that are better adapted to survival in the protected bog, which is now surrounded by suburban residential communities.
"This was likely helped by the large environmental changes occurring over the 1976-2001 time period. Replacement with better-adapted genotypes from external populations may be a common way evolution works in an increasingly human-impacted world," Pergams said.
Lacy studies and compares changes of Volo Bog mice both in the wild and in subsequent generations of their offspring raised in his laboratory.
"It was surprising to us to see how fast genetic and physical change could occur even in the wild population," he said.
Pergams said a lesson of the surprisingly fast replacement of the mouse types is not to assume that animal populations are constant. He also said there's a message for environmentalists.
"Humans are changing the global environment at unprecedented rates," he said. "Plants and animals react to these massive environmental changes either by going extinct or [by] adapting very rapidly."
Source: Paul Francuch
University of Illinois at Chicago
Oliver Pergams, visiting research assistant professor of biological sciences at the University of Illinois at Chicago, and Robert Lacy, population geneticist and conservation biologist at the Chicago Zoological Society, compared the genetic makeup of 115 white-footed mice in the Volo Bog State Natural Area northwest of Chicago using mitochondrial DNA taken from collection samples as old as 150 years and mice collected in recent years.
They found a new type of mouse replaced the old type in Volo Bog between 1976 and 2001.
"The new mice were genetically very different," says Pergams. Structural changes were readily apparent. "Looking at size and shape, the new mice were much bigger and a little flatter."
Pergams and Lacy report the findings in Molecular Ecology, Volume 17, now online, and in print in late December.
Pergams and UIC biological sciences professor Mary Ashley reported in 2001 on similar morphological changes in size and shape over the past century of two widely disparate habitats and species -- deer mice on three different California Channel Islands, and black rats from two Galapagos Islands. While Pergams found these coincidental changes surprising, he said it is too soon to say if this is somehow related to world climate change.
Pergams said the Volo Bog change is best explained by the old mice being replaced by new mice migrating from distinct neighboring populations that are better adapted to survival in the protected bog, which is now surrounded by suburban residential communities.
"This was likely helped by the large environmental changes occurring over the 1976-2001 time period. Replacement with better-adapted genotypes from external populations may be a common way evolution works in an increasingly human-impacted world," Pergams said.
Lacy studies and compares changes of Volo Bog mice both in the wild and in subsequent generations of their offspring raised in his laboratory.
"It was surprising to us to see how fast genetic and physical change could occur even in the wild population," he said.
Pergams said a lesson of the surprisingly fast replacement of the mouse types is not to assume that animal populations are constant. He also said there's a message for environmentalists.
"Humans are changing the global environment at unprecedented rates," he said. "Plants and animals react to these massive environmental changes either by going extinct or [by] adapting very rapidly."
Source: Paul Francuch
University of Illinois at Chicago
пятница, 12 августа 2011 г.
Why Are Men More Susceptible To Alcoholism?
Alcohol is one of the most commonly abused substances, and men are up to twice as likely to develop alcoholism as women. Until now, the underlying biology contributing to this difference in vulnerability has remained unclear.
A new study published in Biological Psychiatry reveals that dopamine may be an important factor.
Researchers from Columbia and Yale studied male and female college-age social drinkers in a laboratory test of alcohol consumption. After consuming an alcoholic or non-alcoholic drink, each participant underwent a specialized positron emission tomography (PET) scan, an imaging technique that can measure the amount of alcohol-induced dopamine release.
Dopamine has multiple functions in the brain, but is important in this context because of its pleasurable effects when it is released by rewarding experiences, such as sex or drugs.
Despite similar consumptions of alcohol, the men had greater dopamine release than women. This increase was found in the ventral striatum, an area in the brain strongly associated with pleasure, reinforcement and addiction formation.
"In men, increased dopamine release also had a stronger association with subjective positive effects of alcohol intoxication," explained Dr. Nina Urban, corresponding author for this study. "This may contribute to the initial reinforcing properties of alcohol and the risk for habit formation."
Dr. Anissa Abi-Dargham, senior author on this project, notes that "another important observation from this study is the decline in alcohol-induced dopamine release with repeated heavy drinking episodes. This may be one of the hallmarks of developing tolerance or transitioning into habit."
These findings indicate that the ability of alcohol to stimulate dopamine release may play an important and complex role in its rewarding effects and abuse liability in humans. This identification of an in vivo neurochemical mechanism that could help explain the sex difference in alcoholism is an exciting step forward in alcoholism research.
Sources: Elsevier, AlphaGalileo Foundation.
A new study published in Biological Psychiatry reveals that dopamine may be an important factor.
Researchers from Columbia and Yale studied male and female college-age social drinkers in a laboratory test of alcohol consumption. After consuming an alcoholic or non-alcoholic drink, each participant underwent a specialized positron emission tomography (PET) scan, an imaging technique that can measure the amount of alcohol-induced dopamine release.
Dopamine has multiple functions in the brain, but is important in this context because of its pleasurable effects when it is released by rewarding experiences, such as sex or drugs.
Despite similar consumptions of alcohol, the men had greater dopamine release than women. This increase was found in the ventral striatum, an area in the brain strongly associated with pleasure, reinforcement and addiction formation.
"In men, increased dopamine release also had a stronger association with subjective positive effects of alcohol intoxication," explained Dr. Nina Urban, corresponding author for this study. "This may contribute to the initial reinforcing properties of alcohol and the risk for habit formation."
Dr. Anissa Abi-Dargham, senior author on this project, notes that "another important observation from this study is the decline in alcohol-induced dopamine release with repeated heavy drinking episodes. This may be one of the hallmarks of developing tolerance or transitioning into habit."
These findings indicate that the ability of alcohol to stimulate dopamine release may play an important and complex role in its rewarding effects and abuse liability in humans. This identification of an in vivo neurochemical mechanism that could help explain the sex difference in alcoholism is an exciting step forward in alcoholism research.
Sources: Elsevier, AlphaGalileo Foundation.
вторник, 9 августа 2011 г.
The Beauty Of Nature And How Size Matters Could Impact On Sustainable Energy
The beauty of nature is partly due to the uniformity of leaf and flower size in individual plants, and scientists have discovered how plants arrive at these aesthetic proportions.
Researchers at the John Innes Centre in Norwich have discovered that cells at the margins of leaves and petals play a particularly important role in setting their size.
"The remarkable uniformity of leaves and flowers helps us to tell different species apart, such as daisies and marguerites, which look very similar otherwise. We are now uncovering how the genetic blueprint of a species tightly controls the size of leaves and flowers", says Dr. Michael Lenhard, who led the research.
The cells at the margins seem to secrete a mobile growth signal that keeps the cells throughout the leaf dividing. The more of this signal is produced, the larger the leaves and flowers get.
Surprisingly, this signal seems to be distinct from the classical and well-studied plant hormones that are known to influence growth and development.
"As the signal only seems to come in from the margins, we suggest it gets diluted as the leaf or petal grows. Once the concentration falls below a certain threshold, the cells in the leaf or petal stop dividing. This would be a simple way of measuring the size of a growing organ", says Dr. Lenhard. "It's a bit like adding more and more tonic to a gin and tonic until you can no longer taste the gin."
Strikingly, animals seem to use the same principle of dilution for measuring size, for example of the wings in a fly, although the molecules used are very different.
Efforts are under way to use this discovery to increase leaf growth in biofuel crops for the generation of sustainable energy and to boost the yield of fruits and seeds.
This research was performed in collaboration with Dr Christian Fleck and his group at the Physics Department, University of Freiburg, Germany, and was funded by the Deutsche Forschungsgemeinschaft and the BBSRC. It will be published in Developmental Cell on 3 December, 12:00 PM Noon Eastern Time US.
Source: Dr. Michael Lenhard
Norwich BioScience Institutes
Researchers at the John Innes Centre in Norwich have discovered that cells at the margins of leaves and petals play a particularly important role in setting their size.
"The remarkable uniformity of leaves and flowers helps us to tell different species apart, such as daisies and marguerites, which look very similar otherwise. We are now uncovering how the genetic blueprint of a species tightly controls the size of leaves and flowers", says Dr. Michael Lenhard, who led the research.
The cells at the margins seem to secrete a mobile growth signal that keeps the cells throughout the leaf dividing. The more of this signal is produced, the larger the leaves and flowers get.
Surprisingly, this signal seems to be distinct from the classical and well-studied plant hormones that are known to influence growth and development.
"As the signal only seems to come in from the margins, we suggest it gets diluted as the leaf or petal grows. Once the concentration falls below a certain threshold, the cells in the leaf or petal stop dividing. This would be a simple way of measuring the size of a growing organ", says Dr. Lenhard. "It's a bit like adding more and more tonic to a gin and tonic until you can no longer taste the gin."
Strikingly, animals seem to use the same principle of dilution for measuring size, for example of the wings in a fly, although the molecules used are very different.
Efforts are under way to use this discovery to increase leaf growth in biofuel crops for the generation of sustainable energy and to boost the yield of fruits and seeds.
This research was performed in collaboration with Dr Christian Fleck and his group at the Physics Department, University of Freiburg, Germany, and was funded by the Deutsche Forschungsgemeinschaft and the BBSRC. It will be published in Developmental Cell on 3 December, 12:00 PM Noon Eastern Time US.
Source: Dr. Michael Lenhard
Norwich BioScience Institutes
суббота, 6 августа 2011 г.
Improved Quality Of Life For Women On Continuous Oral Contraceptives
Continuous oral contraceptives may be more effective than the standard 28-day birth control pills in suppressing the ovary, according to researchers. They say that the continuous pill also causes a significant improvement in pain and behavioral changes.
"We have provided a biological proof of concept that both the ovary and the lining of the uterus are suppressed better and quicker with the continuous pill than with the cyclic pill. And there is no harmful effect on the lining of the uterus either," said Richard Legro, M.D., professor of obstetrics and gynecology, Penn State College of Medicine and lead author of the study.
Standard 28-day birth control pills mimic a woman's natural menstrual cycle, while preventing pregnancy. A standard dose includes 21 hormone pills to suppress growth in the endometrium, the lining of the uterus, and seven placeholder placebo pills.
Continuous oral contraceptives may be more effective in treating several medical conditions, where continuous ovarian suppression is desired, such as acne, hirsutism, premenstrual syndrome, endometriosis and polycystic ovary syndrome. But there have been few detailed studies of ovarian function on the pill to demonstrate this effect.
Legro and his colleagues compared the effectiveness of continuous oral contraceptives with that of the cyclical pills. The researchers monitored 62 healthy women, randomly assigned to receive either cyclical or continuous birth control pills, for six months with both researchers and participants blinded to the study group.
"We monitored vaginal bleeding, quality of life, and ovarian and endometrial suppression," said Legro, whose team's findings appeared in a recent issue of the Journal of Clinical Endocrinology and Metabolism.
The researchers found a significant decrease in moderate to heavy bleeding days among women who received the continuous birth control regimen. Women in the continuous group also had a significant decline in circulating and urinary estrogen levels, total ovarian volume and lead follicle size - all biomarkers that indicate the ovary is less active - and reported less pain and behavioral changes compared to women in the cyclic group.
However, results from the study also indicate greater breakthrough bleeding, or spotting, among women in the continuous group. Legro says that while greater breakthrough bleeding may be a truly objectionable side effect for many women, it does not seem to affect their quality of life.
"That is one of the unique things of this study. The quality of life did not necessarily decrease as it was counterbalanced by improvements in other areas such as pain and mood swings," the Penn State researcher added.
According to Legro, the study suggests that there may be diverse mechanisms of breakthrough bleeding depending on whether a woman is using either a cyclical or continuous regimen of birth control pills.
In the case of cyclic pills, the ovary comes back into the equation during the pill free interval leading to a rebound increased secretion of ovarian hormones, which in turn contributes to some breakthrough bleeding, he explained.
"Breakthrough bleeding in the continuous group, in our opinion, is most likely due to the fact that the pill does too good of a job in suppressing the ovary and the lining of the uterus gets a little bit thin and fragile so that from time to time there is a little bit of bleeding," added Legro, whose work is funded by the National Institutes of Health.
The study provides a physical reason for continuous oral contraceptive pills to treat such chronic medical conditions such as polycystic ovary syndrome, endometriosis and premenstrual syndrome, where additional suppression of the ovary or the endometrium is desired, and Legro noted that other chronic conditions such as hypertension or diabetes are treated continuously, not three weeks out of four. Further studies showing a favorable risk benefit ratio of continuous oral contraceptives on these disorders are the next step.
Other researchers on the paper are Jaimey G. Pauli, M.D.; Allen R. Kunselman, senior research assistant; Richard J. Zaino, M.D., professor of anatomic pathology; Laurence M. Demers, M.D., distinguished professor emeritus; Carol L. Gnatuk, M.D.; and William C. Dodson, M.D., all at Penn State College of Medicine; and Juliana W. Meadows, Ph.D., and James Kesner, Ph.D., both at the National Institute for Occupational Safety and Health, Cincinnati, Ohio.
Source: Amitabh Avasthi
Penn State
"We have provided a biological proof of concept that both the ovary and the lining of the uterus are suppressed better and quicker with the continuous pill than with the cyclic pill. And there is no harmful effect on the lining of the uterus either," said Richard Legro, M.D., professor of obstetrics and gynecology, Penn State College of Medicine and lead author of the study.
Standard 28-day birth control pills mimic a woman's natural menstrual cycle, while preventing pregnancy. A standard dose includes 21 hormone pills to suppress growth in the endometrium, the lining of the uterus, and seven placeholder placebo pills.
Continuous oral contraceptives may be more effective in treating several medical conditions, where continuous ovarian suppression is desired, such as acne, hirsutism, premenstrual syndrome, endometriosis and polycystic ovary syndrome. But there have been few detailed studies of ovarian function on the pill to demonstrate this effect.
Legro and his colleagues compared the effectiveness of continuous oral contraceptives with that of the cyclical pills. The researchers monitored 62 healthy women, randomly assigned to receive either cyclical or continuous birth control pills, for six months with both researchers and participants blinded to the study group.
"We monitored vaginal bleeding, quality of life, and ovarian and endometrial suppression," said Legro, whose team's findings appeared in a recent issue of the Journal of Clinical Endocrinology and Metabolism.
The researchers found a significant decrease in moderate to heavy bleeding days among women who received the continuous birth control regimen. Women in the continuous group also had a significant decline in circulating and urinary estrogen levels, total ovarian volume and lead follicle size - all biomarkers that indicate the ovary is less active - and reported less pain and behavioral changes compared to women in the cyclic group.
However, results from the study also indicate greater breakthrough bleeding, or spotting, among women in the continuous group. Legro says that while greater breakthrough bleeding may be a truly objectionable side effect for many women, it does not seem to affect their quality of life.
"That is one of the unique things of this study. The quality of life did not necessarily decrease as it was counterbalanced by improvements in other areas such as pain and mood swings," the Penn State researcher added.
According to Legro, the study suggests that there may be diverse mechanisms of breakthrough bleeding depending on whether a woman is using either a cyclical or continuous regimen of birth control pills.
In the case of cyclic pills, the ovary comes back into the equation during the pill free interval leading to a rebound increased secretion of ovarian hormones, which in turn contributes to some breakthrough bleeding, he explained.
"Breakthrough bleeding in the continuous group, in our opinion, is most likely due to the fact that the pill does too good of a job in suppressing the ovary and the lining of the uterus gets a little bit thin and fragile so that from time to time there is a little bit of bleeding," added Legro, whose work is funded by the National Institutes of Health.
The study provides a physical reason for continuous oral contraceptive pills to treat such chronic medical conditions such as polycystic ovary syndrome, endometriosis and premenstrual syndrome, where additional suppression of the ovary or the endometrium is desired, and Legro noted that other chronic conditions such as hypertension or diabetes are treated continuously, not three weeks out of four. Further studies showing a favorable risk benefit ratio of continuous oral contraceptives on these disorders are the next step.
Other researchers on the paper are Jaimey G. Pauli, M.D.; Allen R. Kunselman, senior research assistant; Richard J. Zaino, M.D., professor of anatomic pathology; Laurence M. Demers, M.D., distinguished professor emeritus; Carol L. Gnatuk, M.D.; and William C. Dodson, M.D., all at Penn State College of Medicine; and Juliana W. Meadows, Ph.D., and James Kesner, Ph.D., both at the National Institute for Occupational Safety and Health, Cincinnati, Ohio.
Source: Amitabh Avasthi
Penn State
среда, 3 августа 2011 г.
Hepatitis C Virus Channels Efforts Into Cell Survival
Researchers at the University of Leeds have discovered a previously unknown mechanism that allows the hepatitis C virus (HCV) to remain in the body for decades.
A study published in the Proceedings of the National Academy of Sciences (PNAS) shows that the virus blocks the actions of a specific ion channel in the cell membrane that would usually trigger apoptosis - the cell's self-destruct programme - and in doing so, has evolved another way of protecting itself from being eliminated from the body.
Apoptosis occurs naturally in the body to allow the removal of unhealthy cells or the replacement of worn-out cells. One of the ways in which apoptosis can be triggered in a cell is to reduce its potassium levels. This can happen when the cell is exposed to oxidative stress that activates a specific ion channel (which acts as a pore in the cell membrane) causing it to open and allow out potassium ions.
However, the research team has discovered that a protein made by HCV, known as NS5A, is able to block the activation of this ion channel in liver cells, enabling these cells to resist cell death for longer.
"For a virus to persist in the body over a long time, it has to find a way of manipulating the host cell so that it becomes resistant to apoptosis," says lead researcher Professor Mark Harris of the University's Faculty of Biological Sciences. "We know of many ways that viruses have evolved to do this, but this is the first observation of a virus preventing cell death by manipulating an ion channel."
HCV affects some 170 million people globally and only around half of these will respond to treatment. Many sufferers will be asymptomatic - some for twenty or even thirty years - but the virus remains in the liver, and its long-tem damage can ultimately cause cirrhosis or cancer.
"Cells in the liver are often exposed to high levels of oxidative, and other, stresses as they work to detoxify the blood of foreign compounds such as drugs and alcohol, and to remove chemicals produced by our own bodies," says Professor Harris. "In addition, the virus itself causes oxidative stress as it replicates in the cells. The research shows that the virus has evolved another way of protecting itself from this natural process, and to avoid elimination from the body for longer."
The research team believes that continued research may offer a potential target for drug development, perhaps through combination therapy.
"We need to find out exactly how the blocking action works, but it's possible that two drugs could be coupled together, one to prevent the virus from blocking the ion channel and another to induce stress to force apoptosis," says Professor Harris.
"It's a very exciting discovery, and ideally we'd like to expand our investigations to see whether other viruses that cause long term or chronic infections - such as HIV - have evolved the same ability."
The research was funded by the Medical Research Council.
Source:
Clare Elsley
University of Leeds
A study published in the Proceedings of the National Academy of Sciences (PNAS) shows that the virus blocks the actions of a specific ion channel in the cell membrane that would usually trigger apoptosis - the cell's self-destruct programme - and in doing so, has evolved another way of protecting itself from being eliminated from the body.
Apoptosis occurs naturally in the body to allow the removal of unhealthy cells or the replacement of worn-out cells. One of the ways in which apoptosis can be triggered in a cell is to reduce its potassium levels. This can happen when the cell is exposed to oxidative stress that activates a specific ion channel (which acts as a pore in the cell membrane) causing it to open and allow out potassium ions.
However, the research team has discovered that a protein made by HCV, known as NS5A, is able to block the activation of this ion channel in liver cells, enabling these cells to resist cell death for longer.
"For a virus to persist in the body over a long time, it has to find a way of manipulating the host cell so that it becomes resistant to apoptosis," says lead researcher Professor Mark Harris of the University's Faculty of Biological Sciences. "We know of many ways that viruses have evolved to do this, but this is the first observation of a virus preventing cell death by manipulating an ion channel."
HCV affects some 170 million people globally and only around half of these will respond to treatment. Many sufferers will be asymptomatic - some for twenty or even thirty years - but the virus remains in the liver, and its long-tem damage can ultimately cause cirrhosis or cancer.
"Cells in the liver are often exposed to high levels of oxidative, and other, stresses as they work to detoxify the blood of foreign compounds such as drugs and alcohol, and to remove chemicals produced by our own bodies," says Professor Harris. "In addition, the virus itself causes oxidative stress as it replicates in the cells. The research shows that the virus has evolved another way of protecting itself from this natural process, and to avoid elimination from the body for longer."
The research team believes that continued research may offer a potential target for drug development, perhaps through combination therapy.
"We need to find out exactly how the blocking action works, but it's possible that two drugs could be coupled together, one to prevent the virus from blocking the ion channel and another to induce stress to force apoptosis," says Professor Harris.
"It's a very exciting discovery, and ideally we'd like to expand our investigations to see whether other viruses that cause long term or chronic infections - such as HIV - have evolved the same ability."
The research was funded by the Medical Research Council.
Source:
Clare Elsley
University of Leeds
Подписаться на:
Комментарии (Atom)