Broccoli and cabbage’s anticancer benefits probed
Nutraingredients.com 28-Jan-2009
Texan researchers have identified a pathway to explain how a compound in cruciferous vegetables like broccoli may protect against pancreatic cancer.
The tissue of cruciferous vegetables, like broccoli, cauliflower, cabbage and Brussels sprouts, contain high levels of the active plant chemicals glucosinolates. These are metabolised by the body into isothiocyanates, which are known to be powerful anti-carcinogens.
Ravi Sahu and Sanjay Srivastava from Texas Tech University Health Sciences Center in Amarillo report that the one such isothiocyanates - benzyl isothiocyanate (BITC) - may be protecting against tumours in the pancreas via a mechanism dependent on the protein STAT-3.
The results, published online ahead of print in the Journal of the National Cancer Institute, study extends out understanding of the potential anti-cancer benefits of such vegetables, and may offer important information to companies involved in the production of extracts for the functional food and dietary supplements industry.
Supplements containing broccoli extracts are available on the market, such as Cyvex Nutrition's BroccoPlus and BroccoPhane, delivering high doses of glucosinolates in powder form.
Study details
Sahu and Srivastava investigated the effects of BITC on pancreatic cancer cell lines grown in culture and on a mouse model of pancreatic cancer. Using different BITC concentrations ranging from five to 40 micromoles, the researchers incubated the human cells with the compound and studied how STAT-3 protein activation was affected.
According to background information from the authors, the STAT-3 protein promotes the survival and proliferation of cancer cells.
Exposure of the cells to BITC reportedly increased cell death (apoptosis) by reducing the amount of activated STAT-3 protein. When cells were used that over-expressed STAT-3 the protective effect of BITC was eliminated, they said.
Importantly, the researchers added that the health of normal pancreatic cells was not affected by BITC.
"Taken together, these findings may provide the basis for further preclinical and clinical investigation of BITC for the chemoprevention and/or chemotherapy of pancreatic cancer," concluded the authors.
Considerations
Sahu and Srivastava noted the limitations of their study, including that only a small number of animals were used. Moreover, these in vitro and in vivo studies can not be directly translated to humans, and significant further studies are needed to deepen the understanding of how STAT-3 affects pancreatic cancer development, and the potentially protective benefits of cruciferous vegetables and their compounds.
Pancreatic cancer is the eighth most common cancer in women, and the 11th most common cancer in men in the UK. Each year, there are almost 3,600 new cases in women, and over 3,300 cases in men.
Source: Journal of the National Cancer Institute
Published online ahead of print, doi:10.1093/jnci/djn470
"The Role of STAT-3 in the Induction of Apoptosis in Pancreatic Cancer Cells by Benzyl Isothiocyanate"
US-Danish alliance in search of healthier foods
Foodnavigator.com, 27-Jan-2009
A new consortium of leading American and Danish food scientists has been established to develop new ingredients for tackling malnutrition and diet-related diseases.
The Transatlantic Foods for Health project is a collaboration between scientists at the University of California, Davis, and four Danish Universities, intended to draw on the two nations’ complementary areas of food research expertise.
The plan is to develop healthier foods and foods with added health benefits through a combination of different research approaches.
One of the program participants is associate professor and lipidologist Lars Hellgren of the Department for Systems Biology at the Technical University of Denmark. He told FoodNavigator-USA.com: “While we in Denmark are very strong on general and technological issues, our colleagues in California are strong on the medical, clinical side. Combining the two together creates an enormous synergy.”
Health benefits
Part of the group’s research is expected to focus on ingredients said to produce specific health benefits, such as the effects of fibers and antioxidants produced from biomass on gut flora, and to examine their effects on a molecular level.
Other areas which are expected to be put under the spotlight include ingredients’ effects on the immune system and cardiovascular health, as well as those that help weight loss or prevent weight gain. In this area, the group says it will be looking at ways ingredients can improve satiety, speed metabolism or reduce the amount of fat that is absorbed from foods by the body.
“It is partly about single ingredients but it’s also about combining ingredients in the right way,” said Hellgren. “I’m interested in fatty acids. The benefits of fatty acids and omega-3 in particular are very well documented, but there is still an issue about how we get it into the food and finding the best formulation.”
He said that although the food industry is not formally involved with the project, both the Danish researchers and Americans “have very strong links with the food industry” in their respective countries.
Nutritional accessibility
Apart from researching ingredients that could help deal with weight-related illnesses, the project also aims to tackle issues of malnutrition.
UC Davis nutrition professor and director of the Foods for Health Institute M.R.C. Greenwood said: “This is not about just adding more vitamin A to carrots… Often, consumers have to pay up to 20 times more for 1,000 healthy calories in fruit and vegetables than they would pay for 1,000 unhealthy calories in, for example, fast food. We have to look at how we get more healthy properties into food that is safe, convenient and economically accessible.”
Greenwood also underlined the importance of continuing to work together with the food industry in order to produce more foods that fit with nutritional guidelines.
Human brain makes snap decision on fat content: Study
Foodnavigator.com, 27-Jan-2009
A new study from Nestle has revealed that the human brain makes quick decisions on the energy and fat content in food just by looking at it – a finding that adds to knowledge on why we choose to eat the foods we do.
Considerable attention is being paid to the energy load of foods, and in particular the saturated fat content, as the world grapples with an obesity epidemic that risks putting enormous strain on health care budgets.
Major food companies need to show they are on-board with healthier eating messages – but the foods they produce must also be acceptable to consumer palates, and cater to the demand for indulgent ‘treat’ foods.
The researchers involved in the new study, published in the journal Neuroimage, note that the fat component in food has a strong influence on texture and palatability – as well as on the body’s energetic balance and its supply of essential fatty acids.
“High fat foods are often consumed with more pleasure, and in larger quantities than healthier foods like vegetables. Such hedonic drives can produce inappropriate eating behaviors, obesity, diabetes, and hypertension,” wrote the researchers, led by Micah Murray.
They propose that food evaluation based on visual information before it is eaten might be the perceptual stage at which the individual makes nutritional choices.
Study details
The study involved 19 adults aged between 25 and 49 years, who were shown images of food and non-foods and asked to discriminate between them. Unbeknownst to the participants, the images of food were also divided into low-fat and high-fat.
Their brain activity was measured electo-encephalography technology.
Murray’s team found that the human brain assesses the reward properties of a food very quickly, and in parallel with the brain regions responsible for categorization and decision-making.
This is said to be the first time such processes have been investigated in humans, giving an indication of the brain regions where food choices are made.
“We discovered that the adult brain can estimate the fat content of food simply from visual information, and that this process happens within 200 milliseconds,” said Nestle research scientist Julie Hundry.
Specifically, the brain made very rapid distinctions between the high- and low-fat foods; moreover, the regions of the brain that are typically associated with assessing the likely reward from an action and making decisions were seen to respond more strongly to high-fat foods than to low-fat.
“These results will help Nestle understand how the brain processes and interprets the nutritional value of food.”
The research was a collaborative project between the Nestle Research Center, the Centre Hospitalier Universitaire Vaudois and the University of Lausanne Centre d’Imagerie Biomedicale.
Neuroimage
doi:10.1016/j.neuroimage.2008.10.005
“The brain tracks the energetic value in food images” Authors: Ulrike Toepel, Jean-François Knebel, Julie Hudry, Johannes le Coutre and Micah M. Murray
Cruciferous Vegetables Proven to Prevent Breast Cancer
(NaturalNews) Research is continually showing the benefits of eating a diet high in cruciferous vegetables such as broccoli, cauliflower, Brussels sprouts and cabbage. These veggies have been proven to prevent all sorts of cancer, including breast cancer. The way in which the active compounds in cruciferous vegetables inhibit breast cancer cells has been largely unknown. Now a study at UC Santa Barbara has shown why they are so effective.
Breast cancer is currently the second leading cause of cancer deaths in women. Consuming too many dead foods that don't offer anything of value to the body is one of the root causes. Adding cruciferous vegetables to the diet can fight this epidemic form of cancer.
Olga Azarenko, a graduate student at UCSB who worked on the team said, "These vegetables contain compounds called isothiocyanates which we believe to be responsible for the cancer-preventive and anti-carcinogenic activities in these vegetables. Broccoli and broccoli sprouts have the highest amount of the isothiocyanates.
"Our paper focuses on the anti-cancer activity of one of these compounds, called sulforaphane, or SFN," Azarenko added. "It has already been shown to reduce the incidence and rate of chemically induced mammary tumors in animals. It inhibits the growth of cultured human breast cancer cells, leading to cell death."
Isothiocyanate have the power to actually make changes on a genetic level. They can activate some genes that fight cancer and switch off others that fuel tumors.
Cruciferous vegetables prevent all sorts of cancer. One study of 50,000 men studied how different fruits and vegetables prevented bladder cancer. No significant associations were found between bladder cancer and the consumption of:
? Total fruits and vegetables
? Fruits only
? Vegetables only
? Yellow vegetables
? Green leafy vegetables
However, there was a 51 percent risk reduction for bladder cancer in those consuming more than 5 servings of cruciferous vegetables a week versus those consuming less than one a week.
Another study of 1000 men revealed that men who consumed 3 or more servings of cruciferous vegetables per week had a 41 percent reduced risk of prostate cancer compared to those that consumed only one or less a week.
Other studies have shown that broccoli sprouts are a natural sunscreen, protecting against skin cancer.
If everyone in the world ate at least 5 servings of cruciferous vegetables per week, we would see major shifts in health. Cruciferous vegetables are incredibly easy to add into the diet. Finely chopping raw broccoli and Brussels sprouts and sprinkling them over food will help them easily blend into other flavors. Adding broccoli sprouts is another way to get the incredible benefits of isothiocyanates.
Carcinogenesis December 2008; 29(12):2360-8
http://www.naturalnews.com/025441.html
Genetically Modified Food Researchers Want Crop Trial Locations Kept Secret
(NaturalNews) Scientists involved in the genetic modification of food crops have called on the British government to pass laws making experimental crop test sites secret.
Currently, European Union rules require that all test plot locations for genetically modified (GM) crops be made public. According to senior researchers, this information is frequently used by protesters seeking to disrupt the trials. The consistent sabotage of GM test sites has led to a steep drop in such research in the United Kingdom. According to Jim Dunwell of Reading University, there has been only one application for a GM crop trial in the making them in 2008, compared to an average of 20 to 30 per year back in the late 1990s.
For those still in the GM research business, fear of sabotage has driven up costs.
"We now have 24-hour security, we have fences around materials," said Wayne Powell of the National Institute of Agricultural Botany in Cambridge.
Critics of GM foods have opposed the move to make the trials secret.
"Friends of the Earth would have deep concerns about making them secret because of the potential risks that they pose," said Claire Oxborough of Friends of the Earth. "[These crops] are at the very early stages of development - we don't know the impact they'll have on the environment and on health, and very often these trials are not set up to look at that."
The public needs to be well informed about GM crop trials in order to carefully monitor them for potential risks, Oxborough said.
"What you don't want to do is get into a situation where in rural communities you have an air of distrust - rumors, speculation going on because no one knows what their neighbors might be growing," she said. "We need transparency - we need to know where these field trials are taking place so that farmers and the public can be adequately protected."
http://www.naturalnews.com/025435.html
Studies find mercury in much U.S. corn syrup
Tue Jan 27, 2009 6:15pm GMT
WASHINGTON (Reuters) - Many common foods made using commercial high fructose corn syrup contain mercury as well, researchers reported on Tuesday, while another study suggested the corn syrup itself is contaminated.
Food processors and the corn syrup industry group attacked the findings as flawed and outdated, but the researchers said it was important for people to know about any potential sources of the toxic metal in their food.
In one study, published in the journal Environmental Health, former Food and Drug Administration scientist Renee Dufault and colleagues tested 20 samples of high fructose corn syrup and found detectable mercury in nine of the 20 samples.
Dufault said in a statement that she told the FDA about her findings but the agency did not follow up.
Dr. David Wallinga, a food safety researcher and activist at the nonprofit Institute for Agriculture and Trade Policy, said he followed up on the report to find mercury in actual food.
"When I learned of that work, I said that is interesting but we don't just go out and eat a spoonful of high fructose corn syrup," Wallinga said in a telephone interview.
"We went and looked at supermarket samples where high fructose corn syrup was the first or second ingredient on the label," he said. These 55 different foods included barbecue sauce, jam, yogurt and chocolate syrup.
"We found about one out of three had mercury above the detection limit," Wallinga said.
The Corn Refiners Association challenged the findings.
"This study appears to be based on outdated information of dubious significance," the group said in a statement.
Wallinga and colleagues said they believed the mercury got into the food during manufacture, at plants that use mercury-grade caustic soda produced in industrial chlorine plants, although his team was unable to show this.
"Our industry has used mercury-free versions of the two reagents mentioned in the study, hydrochloric acid and caustic soda, for several years," Audrae Erickson, president of the Corn Refiners Association, said in a statement.
Wallinga said the studies were based on samples taken in 2005, the most recent available.
Many studies have shown that fish can be high in mercury. Wallinga said consumers should know about other potential sources so they can limit how much they eat. "The best mercury exposure is no exposure at all," he said.
"Even at low levels methylmercury can harm the developing brain. The last thing we should intentionally do is add to it," Wallinga added.
He said his team did not test foods that did not contain corn syrup to see if they were also high in mercury.
Eat less to remember more, study suggests
Last Updated: 2009-01-27 17:00:24 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Cutting calories may improve memory among healthy elderly men and women, a new study from Germany hints. In the study, researchers found that people who cut their calorie intake by approximately 30 percent performed better on standard memory tests after just three months.
"Our study may help to generate novel prevention strategies to maintain cognitive functions into old age," Dr. A. Veronica Witte and colleagues from University of Munster wrote in the latest issue of Proceedings of the National Academy of Sciences.
Animal studies have shown that diets low in calories and rich in unsaturated fatty acids - the kind found in olive oil and fish - are beneficial for brain function, helping to improve memory in aging rats.
To see whether the same effects can be induced in humans, Witte's team divided 50 normal- to overweight individuals whose average age was 60 years into three groups. One group restricted by up to 30 percent the amount of calories they consumed; a second group increased their consumption of unsaturated fatty acids by up to 20 percent; and a third group, serving as the control group, made no changes.
According to the investigators, the calorie-restricted group saw a significant 20 percent average increase in verbal memory scores after 3 months. In contrast, no significant changes in memory performance emerged in the two other groups.
The investigators also noticed that memory improvements in the calorie-restricted group correlated with decreases in insulin levels and "biomarkers" of inflammation in the body, and that these changes were most pronounced in those individuals who stuck closest to the prescribed calorie-restricted diet.
"To our knowledge, the current results provide the first experimental evidence in humans that caloric restriction improves memory in the elderly," Witte and colleagues note.
The results of this study, they add, "may help to develop new prevention and treatment strategies for maintaining cognitive health into old age."
SOURCE: Proceedings of the National Academy of Sciences, January 27, 2009.
http://www.reutershealth.com/archive/2009/01/27/eline/links/20090127elin007.html
US Senator eyes $12.4 bln for health care stimulus
Last Updated: 2009-01-27 13:00:46 -0400 (Reuters Health)
WASHINGTON (Reuters) - The chairman of a U.S. Senate Appropriations subcommittee outlined $12.4 billion in health care spending on Monday for inclusion in the economic stimulus package being written by Congress.
The panel leader, Democrat Tom Harkin of Iowa, said he would pursue the funding when the Appropriations subcommittee on health drafts its part of the legislation.
The meeting is scheduled for Tuesday and the outlook is good for approval, he said.
During a speech to the National Rural Health Association, Harkin called for $5.8 billion for wellness and preventive care, $5 billion to build and renovate community health care facilities, $1 billion for health care technology and $600 million to aid education and training of health care workers.
Harkin said health care reform should place more emphasis on preventive.
EU scientific body raises health alarm on MP3s
Last Updated: 2009-01-27 15:03:24 -0400 (Reuters Health)
BRUSSELS (Reuters) - Up to 10 million young Europeans are in danger of damaging their hearing by playing their MP3 personal music players too loud, a European Union body on health risks told a conference on Tuesday.
Listening to MP3 players and other personal music players at high volumes for long periods of time can cause loss of hearing and tinnitus, a ringing sensation in the ears, the EU Scientific Committee on Emerging and Newly Identified Health Risks said.
It found that 5-10 percent of MP3 users risk permanent hearing loss if they listen to a personal music player for more than one hour per day, each week at high volume settings for a period of at least 5 years. No cure is currently known for hearing loss or tinnitus, the committee noted in its report.
"Let's be frank -- we are looking at a catastrophe unless something is done soon," Stephen Russell of the pan-European ANEC consumer safety group said.
The conference, organised by the European Commission in Brussels, discussed possible measures to prevent such health effects, ranging from warnings flashed on the devices' screens, to limits on the maximum volumes on players. The Commission said it would examine possible action on the problem.
http://www.reutershealth.com/archive/2009/01/27/eline/links/20090127elin017.html
Reducing Salt Intake Isn't The Only Way To Reduce Blood Pressure
ScienceDaily (Jan. 28, 2009) — Most people know that too much sodium from foods can increase blood pressure. A new study suggests that people trying to lower their blood pressure should also boost their intake of potassium, which has the opposite effect to sodium.
Researchers found that the ratio of sodium-to-potassium in subjects' urine was a much stronger predictor of cardiovascular disease than sodium or potassium alone.
"There isn't as much focus on potassium, but potassium seems to be effective in lowering blood pressure and the combination of a higher intake of potassium and lower consumption of sodium seems to be more effective than either on its own in reducing the risk of cardiovascular disease," said Dr. Paul Whelton, senior author of the study in the January 2009 issue of the Archives of Internal Medicine. Whelton is an epidemiologist and president and CEO of Loyola University Health System.
Researchers determined average sodium and potassium intake during two phases of a study known as the Trials of Hypertension Prevention. They collected 24-hour urine samples intermittently during an 18-month period in one trial and during a 36-month period in a second trial. The 2,974 study participants initially aged 30-to-54 and with blood pressure readings just under levels considered high, were followed for 10-15 years to see if they would develop cardiovascular disease. Whelton was national chair of the Trials of Hypertension Prevention.
Those with the highest sodium levels in their urine were 20 percent more likely to suffer strokes, heart attacks or other forms of cardiovascular disease compared with their counterparts with the lowest sodium levels. However this link was not strong enough to be considered statistically significant.
By contrast, participants with the highest sodium-to-potassium ratio in urine were 50 percent more likely to experience cardiovascular disease than those with the lowest sodium-to-potassium ratios. This link was statistically significant.
Most previous studies of the relationship between sodium or potassium and cardiovascular disease have had to rely on people's recall or record of what foods they eat to estimate their level of sodium consumption. This is a less precise measure of sodium intake than urine samples. In addition, many have been cross-sectional rather than follow-up studies.
The new study "is a quantum leap in the quality of the data compared to what we have had before," Whelton said.
Whelton was a member of a recent Institute of Medicine panel that set dietary recommendations for salt and potassium. The panel said healthy 19-to-50 year-old adults should consume no more than 2,300 milligrams of sodium per day -- equivalent to one teaspoon of table salt. More than 95 percent of American men and 75 percent of American women in this age range exceed this amount.
To lower blood pressure and blunt the effects of salt, adults should consume 4.7 grams of potassium per day unless they have a clinical condition or medication need that is a contraindication to increased potassium intake. Most American adults aged 31-to-50 consume only about half as much as recommended in the Institute of Medicine report. Changes in diet and physical activity should be under the supervision of a health care professional.
Good potassium sources include fruits, vegetables, dairy foods and fish. Foods that are especially rich in potassium include potatoes and sweet potatoes, fat-free milk and yogurt, tuna, lima beans, bananas, tomato sauce and orange juice. Potassium also is available in supplements.
Whelton is among the nation's top experts on high blood pressure. He has published more than 400 papers on the subject, and has been the principal investigator on more than $100 million of studies funded by the National Institutes of Health.
Co-authors of the Archives study include Nancy Cook (first author), Julie Buring and Dr. Kathryn Rexrode of Brigham and Women's Hospital; Eva Obarzanek and Dr. Jeffrey Cutler of the National Heart, Lung and Blood Institute; Dr. Lawrence Appel of Johns Hopkins University and Shiriki Kumanyika of the University of Pennsylvania.
http://www.sciencedaily.com/releases/2009/01/090126173839.htm
Major Immune System Branch Has Hidden Ability To Learn
ScienceDaily (Jan. 28, 2009) — Half of the immune system has a hidden talent, researchers at Washington University School of Medicine in St. Louis have discovered.
They found the innate immune system, long recognized as a specialist in rapidly and aggressively combating invaders, has cells that can learn from experience and fight better when called into battle a second time. Scientists previously thought any such ability was limited to the immune system's other major branch, the adaptive immune system.
The finding will help scientists better understand the immune system and seek new ways to modulate its responsiveness. Low immune responsiveness like that found in some genetic disorders and conditions like AIDS can leave the body dangerously vulnerable to infection; but too much can put it at risk of autoimmune conditions such as rheumatoid arthritis.
Vaccines take advantage of a property researchers call "immune memory," which is found in adaptive immune cells that can learn to recognize a particular invader and more quickly and forcefully attack the invader if it returns. By exposing the immune system to a weakened or dead version of a pathogen such as measles, a vaccine stimulates the body so that it can much more effectively respond to naturally occurring infections of the same or similar agents.
The new ability scientists identified has a similar result — cells that can fight back more effectively after an initial stimulation – but the cells are not adaptive immune cells. They are the innate immune system's natural killer cells, which can switch between an active infection-fighting state and a dormant resting state.
"We're calling this new property 'memory-like,'" says senior author Wayne M. Yokoyama, M.D., the Sam J. and Audrey Loew Levin Professor of Medicine. "Natural killer cells can't specialize in recognition of a particular pathogen, but we found that once they've been activated, they can respond more easily and effectively to the next call for activation."
Previous efforts to learn what happens to natural killer cells after activation were hampered by the fact that the cells do not return to a resting state in cell cultures. This shortens their already brief life spans, which are measured in weeks.
To overcome this, lead author Megan A. Cooper, M.D., Ph.D., a postdoctoral fellow in pediatric rheumatology, activated mouse natural killer cells in culture, stained them with a fluorescent green dye and injected them back into the mice.
Scientists tracked the cells and re-extracted them one to three weeks later. They found the cells had returned to their resting state, but could be reactivated more easily and responded more vigorously to activation. Improved responses included increased cell replication and production of interferon gamma, a compound that has anti-pathogen activities and helps spread the immune response by activating additional immune cells. This appeared to be true of both the original cells and their descendants, identifiable by reduced levels of green dye.
Cooper notes that in newborns and young infants the adaptive immune system is largely unavailable. She speculates that it may one day be possible to help the body defend itself during this period by finding a way to prime this memory-like mechanism in natural killer cells.
"Other innate immune cells may also have similar properties," Yokoyama says. "It should be possible to therapeutically exploit these memory-like properties to make more effective immune cells."
Cooper and Yokoyama, who is a Howard Hughes Medical Institute investigator, plan to further study how natural killer cells acquire their "memories."
Cooper MA, Elliott JM, Keyel PA, Yang L, Carrero JA, Yokoyama WM. Cytokine-induced memory-like natural killer cells. Proceedings of the National Academy of Sciences, January 26, 2009
http://www.sciencedaily.com/releases/2009/01/090126173723.htm
Is Rapid Transition Through Menopause Linked To Earlier Onset Of Heart Disease?
ScienceDaily (Jan. 28, 2009) — An evaluation of 203 women as part of the multifaceted Los Angeles Atherosclerosis Study (LAAS) found that those who transitioned more quickly through menopause were at increased risk for a higher rate of progression of "preclinical atherosclerosis" – narrowing of arteries caused by the thickening of their walls.
Cardiologist C. Noel Bairey Merz, M.D., is principal investigator of the study. She is director of the Women's Heart Center and the Preventive and Rehabilitative Cardiac Center at the Cedars-Sinai Heart Institute. She serves as professor of medicine at Cedars-Sinai and holds the Women's Guild Endowed Chair in Women's Health.
This observational study included 203 women between ages 45 and 60 at the time they entered the study. Fifty-two were premenopausal, 20 were perimenopausal and 131 were postmenopausal. None of the women had been diagnosed with cardiovascular disease. They were evaluated when they entered the study and at two 18-month intervals, providing a snapshot over a three-year period of time.
Evaluations included carotid intimal-media thickness (cIMT) measurements and objective measures of menopausal status based on hormone levels and physiologic changes, not subjective factors, such as hot flashes and estimates of menstrual cycling.
Women who transitioned from being premenopausal to being fully postmenopausal within three years had more buildup of fatty plaque in their carotid arteries, suggesting that women who transition through menopause rapidly are at greater risk of early development of heart disease.
"We know that more fatty plaque accumulation predicts future heart attacks and strokes, but this is our first venture into this particular line of inquiry. This is an observational study, which doesn't provide specific recommendations for patient evaluation and treatment, but it does raise questions," Bairey Merz said.
"The findings suggest that we study this more definitively to possibly determine if women undergoing a more rapid menopause might benefit from early hormone replacement therapy," she said. "In the meantime, physicians could consider using carotid intimal-media thickness measurement or other cardiovascular screenings for women who are rapidly transitioning or who have certain risk factors, such as cigarette smoking or chemotherapy, which are known to accelerate transition through the menopause."
The study should not be used by patients to self-diagnose or presume they may be at higher risk because of symptoms.
"Women will say they're perimenopausal because they're having hot flashes or sleep disturbances or some cycle irregularity, but those are all symptoms. We use a very specific code of definitions to assess hormones and whether or not the ovaries are cycling," Bairey Merz said, adding that all women from the age of 21 should have annual checkups, which include blood pressure, cholesterol, height, weight and other measurements. Those at increased risk for cardiovascular disease may be referred by their physicians for additional screenings.
Funding for this study was provided by a grant from the National Institutes of Health/National Heart, Lung, and Blood Institute.
http://www.sciencedaily.com/releases/2009/01/090127165945.htm
Stress Disrupts Human Thinking, But The Brain Can Bounce Back
ScienceDaily (Jan. 28, 2009) — A new neuroimaging study on stressed-out students suggests that male humans, like male rats, don’t do their most agile thinking under stress. The findings, published this month in the Proceedings of the National Academy of Sciences, show that 20 male M.D. candidates in the middle of preparing for their board exams had a harder time shifting their attention from one task to another than other healthy young men who were not under the gun.
Previous experiments had found that stressed rats foraging for food had similar impairments and that those problems resulted from stress-induced changes in their brain anatomy. The new study, using functional magnetic resonance imaging (fMRI) to scan the stressed students’ brains, is a robust example of how basic research in an animal model can lead to high-tech investigations of the human brain.
“It’s a great translational story,” says Bruce S. McEwen, head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at The Rockefeller University, who worked on the project with colleagues at Weill Cornell Medical College. “The research in the rats led to the imaging work on people, and the results matched up remarkably well.”
The work holds good news too, for both rats and humans: Their brains recuperate quickly. Less than a month after the stress goes away, they are back to normal. “The message is that healthy brains are remarkably resilient and plastic,” McEwen says.
To probe the effects of stress, the researchers scanned the brains of volunteers, some stressed and others relatively relaxed, performing two subtly different kinds of mental tasks, either an attention-shift or a response-reversal. Lying inside the scanner, the subjects looked at two discs: one red and one green, with one moving up and the other down. In a series of trials, they were prompted to choose a disc according to motion or color. By ordering when the subjects did which tasks, they challenged their volunteers’ brains to either switch focus from color to motion, or to suddenly reverse their choice of a disc in the same category.
“It’s like the old story about the American crossing the road in England,” says Conor Liston, an M.D.-Ph.D. student at Rockefeller and Cornell, who led the research. A response-reversal requires the brain to override the habitual impulse to first look left instead of right for oncoming cars. An American in Venice might require an attention-shift, by contrast, to seek out boats instead of evading cars.
In earlier research on rats, neuroscientists found that these two tasks place demands on different circuits in the brain, and the circuits are affected in different ways by stress. In particular, collaborative work by McEwen and John Morrison at Mount Sinai Medical Center have shown that repeated stress on rats shriveled nerve cells of the medial prefrontal cortex, and that a shrunken prefrontal cortex is linked to slower performance on attention-shifting tasks. In those experiments, rats learned to dig through a certain texture, like sawdust, in the presence of an irrelevant odor to find food; then the researchers made odor, rather than texture, the clue for finding the food and measured how long it took the rats to switch their foraging strategies. But while the restricted prefrontal cortex — a larger version of which is thought to play a role in the “executive function” in humans — slowed the rats’ performance on attention-shifts, it did not change their performance on response-reversal tasks. In fact, neurons in a different part of the brain thought to be involved in response-reversals, the orbital frontal cortex, actually grew larger from the stress.
The new research suggests that something very similar may happen to distressed humans. Liston, working with B.J. Casey at the Sackler Institute at Weill Cornell, used fMRI to explore his hunch that the brains of rats and men have some basic processes in common — that stress would also impair performance on attention-shifting tasks and diminish activity in the medial prefrontal cortex.
He found that male med students who said they were stressed out one month before they were to take their boards fared much worse on attention-shifting tasks than similar healthy adults who claimed to be taking it easy. The high stress levels, gauged by an established measure called the perceived stress scale, were also tightly associated with diminished activity in the prefrontal cortex. But their performance on response-reversals was unimpaired. Finally, as was found in the rats, when Liston scanned the students again one month after the test, he discovered that their attention-shifting performance had returned to normal along with their brains.
The uncanny similarities surprised even the researchers. “I certainly don’t want to say that rat brains are just like human brains,” Liston says. “But it does show that you can use research in animal models to help interpret human neuroimaging results.”
Liston plans to next explore how stress impacts the rest of the brain. He also wants to investigate whether or not there are differences in how the brains of men and women respond to stress. “Stress is doing a whole lot of things in your brain that we don’t understand yet, but we know that it is intimately involved in a wide range of neuropsychiatric disorders,” Liston says. A mechanistic understanding of stress could lead to insights into associated psychiatric problems, he says.
Liston et al. Psychosocial stress reversibly disrupts prefrontal processing and attentional control. Proceedings of the National Academy of Sciences, 2009; 106 (3): 912 DOI: 10.1073/pnas.0807041106
http://www.sciencedaily.com/releases/2009/01/090127190442.htm
Climate Change Largely Irreversible For Next 1,000 Years, NOAA Reports
ScienceDaily (Jan. 28, 2009) — A new scientific study led by the National Oceanic and Atmospheric Administration reaches a powerful conclusion about the climate change caused by future increases of carbon dioxide: to a large extent, there’s no going back.
The pioneering study, led by NOAA senior scientist Susan Solomon, shows how changes in surface temperature, rainfall, and sea level are largely irreversible for more than 1,000 years after carbon dioxide (CO2) emissions are completely stopped. The findings appear during the week of January 26 in the Proceedings of the National Academy of Sciences.
“Our study convinced us that current choices regarding carbon dioxide emissions will have legacies that will irreversibly change the planet,” said Solomon, who is based at NOAA’s Earth System Research Laboratory in Boulder, Colo.
“It has long been known that some of the carbon dioxide emitted by human activities stays in the atmosphere for thousands of years,” Solomon said. “But the new study advances the understanding of how this affects the climate system.”
The study examines the consequences of allowing CO2 to build up to several different peak levels beyond present-day concentrations of 385 parts per million and then completely halting the emissions after the peak. The authors found that the scientific evidence is strong enough to quantify some irreversible climate impacts, including rainfall changes in certain key regions, and global sea level rise.
If CO2 is allowed to peak at 450-600 parts per million, the results would include persistent decreases in dry-season rainfall that are comparable to the 1930s North American Dust Bowl in zones including southern Europe, northern Africa, southwestern North America, southern Africa and western Australia.
The study notes that decreases in rainfall that last not just for a few decades but over centuries are expected to have a range of impacts that differ by region. Such regional impacts include decreasing human water supplies, increased fire frequency, ecosystem change and expanded deserts. Dry-season wheat and maize agriculture in regions of rain-fed farming, such as Africa, would also be affected.
Climate impacts were less severe at lower peak levels. But at all levels added carbon dioxide and its climate effects linger because of the ocean.
“In the long run, both carbon dioxide loss and heat transfer depend on the same physics of deep-ocean mixing. The two work against each other to keep temperatures almost constant for more than a thousand years, and that makes carbon dioxide unique among the major climate gases,” said Solomon.
The scientists emphasize that increases in CO2 that occur in this century “lock in” sea level rise that would slowly follow in the next 1,000 years. Considering just the expansion of warming ocean waters—without melting glaciers and polar ice sheets—the authors find that the irreversible global average sea level rise by the year 3000 would be at least 1.3–3.2 feet (0.4–1.0 meter) if CO2 peaks at 600 parts per million, and double that amount if CO2 peaks at 1,000 parts per million.
“Additional contributions to sea level rise from the melting of glaciers and polar ice sheets are too uncertain to quantify in the same way,” said Solomon. “They could be even larger but we just don’t have the same level of knowledge about those terms. We presented the minimum sea level rise that we can expect from well-understood physics, and we were surprised that it was so large.”
Rising sea levels would cause “…irreversible commitments to future changes in the geography of the Earth, since many coastal and island features would ultimately become submerged,” the authors write.
Geoengineering to remove carbon dioxide from the atmosphere was not considered in the study. “Ideas about taking the carbon dioxide away after the world puts it in have been proposed, but right now those are very speculative,” said Solomon.
The authors relied on measurements as well as many different models to support the understanding of their results. They focused on drying of particular regions and on thermal expansion of the ocean because observations suggest that humans are contributing to changes that have already been measured.
Besides Solomon, the study’s authors are Gian-Kasper Plattner and Reto Knutti of ETH Zurich, Switzerland, and Pierre Friedlingstein of Institut Pierre Simon Laplace, Gif-Sur-Yvette, France.
http://www.sciencedaily.com/releases/2009/01/090127163403.htm
Getting Diabetes Before 65 More Than Doubles Risk For Alzheimer's Disease
ScienceDaily (Jan. 28, 2009) — Diabetics have a significantly greater risk of dementia, both Alzheimer's disease — the most common form of dementia — and other dementia, reveals important new data from an ongoing study of twins. The risk of dementia is especially strong if the onset of diabetes occurs in middle age, according to the study.
"Our results . . . highlighted the need to maintain a healthy lifestyle during adulthood in order to reduce the risk of dementia late in life," explained Dr. Margaret Gatz, who directs the Study of Dementia in Swedish Twins.
In a study published in the journal Diabetes, Gatz and researchers from Sweden show that getting diabetes before the age of 65 corresponds to a 125 percent increased risk for Alzheimer's disease. Nearly 21 million people in the United States have diabetes, according to the American Diabetes Association, which publishes the journal.
This risk of Alzheimer's disease or other dementia was significant for mid-life diabetics — as opposed to those who develop diabetes after 65 — even when controlling for family factors. In other studies, genetic factors and childhood poverty have been shown to independently contribute to the risk of both diabetes and dementia.
"Twins provide naturally matched pairs, in which confounding factors such as genetics and childhood environment may be removed when comparisons are made between twins," explained Gatz, professor of psychology, gerontology and preventive medicine at the University of Southern California and foreign adjunct professor of medical epidemiology and biostatistics at the Karolinska Institute in Sweden.
Indeed, the chances of a diabetic developing Alzheimer's disease may be even greater in real life than in the study, the researchers write. They identify several factors that might have led them to underestimate the risk of dementia and Alzheimer's among those who develop diabetes before the age of 65.
Diabetes usually appears at a younger age than dementia does, the researchers note. Diabetes is also associated with a higher mortality rate, which may reduce the size of the sample of older adults. In addition, approximately 30 percent of older adults with diabetes have not been diagnosed.
The results of the study implicate adult choices such as exercise, diet and smoking, as well as glycemic control in patients with diabetes, in affecting risk for Alzheimer's disease and diabetes, according to the researchers.
The sample for the study was 13,693 Swedish twins aged 65 or older in 1998, the year tracking for dementia began. Information about diabetes came from prior surveys of twins and linkage to hospital discharge registry data beginning in the 1960s.
Weili Xu of the Karolinska Institute was the lead author of the study, which was a part of her dissertation research.
The research was supported by grants from the National Institute on Aging, the Alzheimer's Association (U.S.A.), the Swedish Research Council in Medicine, and Swedish Brain Power.
Weili Xu, et al. Mid- and Late-Life Diabetes in Relation to the Risk of Dementia. Diabetes, January 2009
Common Medication Associated With Cognitive Decline In Elderly
ScienceDaily (Jan. 28, 2009) — A study published in Journal of the American Geriatrics Society suggested that the use of certain medications in elderly populations may be associated with cognitive decline. The study examined the effects of exposure to anticholinergic medications, a type of drug used to treat a variety of disorders that include respiratory and gastrointestinal problems, on over 500 relatively healthy men aged 65 years or older with high blood pressure.
Older people often take several drugs to treat multiple health conditions. As some of these drugs also have properties that affect neurotransmitters in the brain that are important to overall brain function, the researchers examined the total effects of all medications taken by the patients, both prescription and over-the-counter, that were believed to affect the function of a particular neurotransmitter, acetylcholine.
The findings show that chronic use of medications with anticholinergic properties may have detrimental effects on memory and the ability to perform daily living tasks, such as shopping and managing finances. Participants showed deficits in both memory and daily function when they took these medications over the course of a year. The degree of memory difficulty and impairment in daily living tasks also increased proportionally to the total amount of drug exposure, based on a rating scale the authors developed to assess anticholinergicity of the drugs.
According to study co-author Dr. Ling Han of the Yale University Department of Internal Medicine, elderly patients may be more vulnerable to these types of medications due to neurological and pharmacokinetical changes related to aging.
“This study extends our previous findings on acute cognitive impairment following recent anticholinergic exposure in older medical inpatients,” says Han. “Prescribing for older adults who take multiple prescription and over-the-counter medications requires careful attention to minimize the risk of potential harms of the drugs while maximizing their health benefits.”
Han et al. Cumulative Anticholinergic Exposure Is Associated with Poor Memory and Executive Function in Older Men. Journal of the American Geriatrics Society, 2008; 56 (12): 2203 DOI: 10.1111/j.1532-5415.2008.02009.x
'Happiness Gap' In The US Narrows
ScienceDaily (Jan. 28, 2009) — Happiness inequality in the U.S. has decreased since the 1970s, according to research published this month in the Journal of Legal Studies.
The study, by University of Pennsylvania economists Betsey Stevenson and Justin Wolfers, found that the American population as a whole is no happier than it was three decades ago. But happiness inequality—the gap between the happy and the not-so-happy—has narrowed significantly.
"Americans are becoming more similar to each other in terms of reported happiness," says Stevenson. "It's an interesting finding because other research shows increasing gaps in income, consumption and leisure time."
The happiness gap between whites and non-whites has narrowed by two-thirds, the study found. Non-whites report being significantly happier than they were in the early 1970s, while whites are slightly less happy. The happiness gap between men and women closed as well. Women have become less happy, while men are a little more cheerful.
One demographic area where the happiness gap increased was in educational attainment. People with a college diploma have gotten happier, while those with a high school education or less report lower happiness levels.
Stevenson and Wolfers used data collected from 1972 to 2006 through the University of Chicago's General Social Survey. Each year, participants were asked, "Taken all together, how would you say things are these days—would you say that you are very happy, pretty happy, or not too happy?"
The proportion of people choosing "pretty happy" has increased from 49 percent in 1972 to 56 percent in 2006. Responses of "very happy" and "not too happy" decreased in relatively equal amounts. This convergence toward the middle response closed happiness gaps in nearly all the demographic groups examined.
"The U.S. population as a whole is not getting happier," Stevenson said. "For every unhappy person who became happier, there's someone on the other side coming down."
The authors say that it's hard to pin down what exactly is causing the narrowing happiness gap. But they suggest that money probably is not the answer.
"That these trends differ from trends in both income growth and income inequality suggests that a useful explanation may lie in the nonpecuniary domain," Stevenson and Wolfers write.
Stevenson et al. Happiness Inequality in the United States. The Journal of Legal Studies, 2008; 37 (s2): S33 DOI: 10.1086/592004
http://www.sciencedaily.com/releases/2009/01/090126121352.htm
Biofuels Ignite Food Crisis Debate
ScienceDaily (Jan. 28, 2009) — Study highlights problems linked to converting crops into biofuels. Taking up valuable land and growing edible crops for biofuels poses a dilemma: Is it ethical to produce inefficient renewable energies at the expense of an already malnourished population?
David Pimentel and his colleagues from Cornell University in New York State highlight the problems linked to converting a variety of crops into biofuels. Not only are these renewable energies inefficient, they are also economically and environmentally costly and nowhere near as productive as projected. Their findings are published online in Springer’s journal Human Ecology.
In the context of global shortages of fossil energy – oil and natural gas in particular – governments worldwide are focusing on biofuels as renewable energy alternatives. In parallel, almost 60 percent of the world’s population is malnourished increasing the need for grains and other basic foods. Growing crops, including corn, sugarcane and soybean, for fuel uses water and energy resources vital for the production of food for human consumption.
Professor Pimentel and his team review the availability and use of land, water and current energy resources globally, and then look at the situation in the US specifically. They also analyze biomass resources and show that there is insufficient US biomass for both ethanol and biodiesel production to make the US oil independent.
Their paper then looks at the efficiency and costs associated with converting a range of crops into energy and shows that in each case more energy is required for this process than they actually produce as fuel. The research finds a negative energy return of 46 percent for corn ethanol, 50 percent for switchgrass, 63 percent for soybean biodiesel and 58 percent for rapeseed. Even the most promising palm oil production results in a minus 8 percent net energy return. There are also a number of environmental problems linked to converting crops for biofuels, including water pollution from fertilizers and pesticides, global warming, soil erosion and air pollution.
In the researchers’ opinion, there is simply not enough land, water and energy to produce biofuels. They also argue that ironically, the US is becoming more oil-dependent, not less, as was intended through the production of biofuels. In most cases, more fossil energy is required to produce a unit of biofuel compared with the energy that it provides. As a result, the US is importing more oil and natural gas in order to make the biofuels.
The authors conclude that “Growing crops for biofuels not only ignores the need to reduce natural resource consumption, but exacerbates the problem of malnourishment worldwide by turning food grain into biofuels…Increased use of biofuels further damages the global environment and especially the world food system.”
Pimentel D et al. Food versus biofuels: environmental and economic costs. Human Ecology, DOI: 10.1007/s10745-009-9215-8
http://www.sciencedaily.com/releases/2009/01/090128074830.htm |
