Posts tagged science

ScienceDaily (July 5, 2012) — The widely used diabetes drug metformin comes with a rather unexpected and alluring side effect: it encourages the growth of new neurons in the brain. The study reported in the July 6th issue of Cell Stem Cell, a Cell Press publication, also finds that those neural effects of the drug also make mice smarter.

New research finds that the widely used diabetes drug metformin comes with a rather unexpected and alluring side effect: it encourages the growth of new neurons in the brain. (Credit: iStockphoto/Guido Vrola)

The discovery is an important step toward therapies that aim to repair the brain not by introducing new stem cells but rather by spurring those that are already present into action, says the study’s lead author Freda Miller of the University of Toronto-affiliated Hospital for Sick Children. The fact that it’s a drug that is so widely used and so safe makes the news all that much better.

Earlier work by Miller’s team highlighted a pathway known as aPKC-CBP for its essential role in telling neural stem cells where and when to differentiate into mature neurons. As it happened, others had found before them that the same pathway is important for the metabolic effects of the drug metformin, but in liver cells.

"We put two and two together," Miller says. If metformin activates the CBP pathway in the liver, they thought, maybe it could also do that in neural stem cells of the brain to encourage brain repair.

The new evidence lends support to that promising idea in both mouse brains and human cells. Mice taking metformin not only showed an increase in the birth of new neurons, but they were also better able to learn the location of a hidden platform in a standard maze test of spatial learning.

While it remains to be seen whether the very popular diabetes drug might already be serving as a brain booster for those who are now taking it, there are already some early hints that it may have cognitive benefits for people with Alzheimer’s disease. It had been thought those improvements were the result of better diabetes control, Miller says, but it now appears that metformin may improve Alzheimer’s symptoms by enhancing brain repair.

Miller says they now hope to test whether metformin might help repair the brains of those who have suffered brain injury due to trauma or radiation therapies for cancer.

Source: Science Daily

ScienceDaily (July 5, 2012) — Although many areas of the human brain are devoted to social tasks like detecting another person nearby, a new study has found that one small region carries information only for decisions during social interactions. Specifically, the area is active when we encounter a worthy opponent and decide whether to deceive them.

(Credit: © wtamas / Fotolia)

A brain imaging study conducted by researchers at the Duke Center for Interdisciplinary Decision Science (D-CIDES) put human subjects through a functional MRI brain scan while playing a simplified game of poker against a computer and human opponents. Using computer algorithms to sort out what amount of information each area of the brain was processing, the team found only one brain region — the temporal-parietal junction, or TPJ — carried information that was unique to decisions against the human opponent.

Some of the time, the subjects were dealt an obviously weak hand. The researchers wanted to see whether they could watch the player calculate whether to bluff his opponent. The brain signals in the TPJ told the researchers whether the subject would soon bluff against a human opponent, especially if that opponent was judged to be skilled. But against a computer, signals in the TPJ did not predict the subject’s decisions.

The TPJ is in a boundary area of the brain, and may be an intersection for two streams of information, said lead researcher McKell Carter, a postdoctoral fellow at Duke. It brings together a flow of attentional information and biological information, such as “is that another person?”

Carter observed that in general, participants paid more attention to their human opponent than their computer opponent while playing poker, which is consistent with humans’ drive to be social.

Throughout the poker game experiment, regions of the brain that are typically thought to be social in nature did not carry information specific to a social context. “The fact that all of these brain regions that should be specifically social are used in other circumstances is a testament to the remarkable flexibility and efficiency of our brains,” said Carter.

"There are fundamental neural differences between decisions in social and non-social situations," said D-CIDES Director Scott Huettel, the Hubbard professor of psychology & neuroscience at Duke and senior author of the study. "Social information may cause our brain to play by different rules than non-social information, and it will be important for both scientists and policymakers to understand what causes us to approach a decision in a social or a non-social manner.

"Understanding how the brain identifies important competitors and collaborators — those people who are most relevant for our future behavior — will lead to new insights into social phenomena like dehumanization and empathy," Huettel added.

Source: Science Daily

ScienceDaily (July 4, 2012) — A study by researchers at Universidad Carlos III de Madrid and Universidad de Zaragoza has determined that when deciding whether to cooperate with others, people do not act thinking about their own reward, as had been previously believed, but rather individuals are more influenced by their own mood at the time and by the number of individuals with whom they have cooperated before.

In addition to previous studies, this research is also based on an experiment carried out by the Institute for Biocomputation and Physics of Complex Systems (BIFI) at the Universidad de Zaragoza, together with the Fundación Ibercivis and Universidad Carlos III de Madrid (UC3M), the largest study of its kind to date in real time regarding cooperation in society. It was carried out during this past December, with 1,200 Aragon secondary students participating, who interacted electronically in real time via a social conflict prototype known as the “Prisoner’s Dilemma.” This game shows that the greatest benefit for individuals who interact is produced when both of them collaborate, but if one collaborates and the other does not, the latter will receive more benefits than the one who cooperates. On occasion, this allows an individual to take advantage of the cooperation of others, but if this tendency is extended, in the end, no one cooperates and as such, nobody obtains rewards.

After analyzing the information, the main conclusion drawn by the researchers is that in a situation where cooperating with others is beneficial, the way the individuals involved are organized into one social structure or another is irrelevant. A first analysis contradicts what many researchers have held based on theoretical studies.

In the experiment, the degree of cooperation in a network in which each subject interacts with four other individuals is compared to a network in which the number of connections vary between 2 and 16, that is, one that is more similar to a social network. What has been observed is that the results in the two networks are identical. “This happens because, contrary to what has been proposed in the majority of studies, people do not make their decisions based on the rewards obtained (by them or by their neighbors), but rather based on how many people have recently cooperated with them, as well as on their own mood at the time,” the researchers explained.

These results help understand how people make decisions, above all in the context in which one has to decide between collaborating with or taking advantage of others. “Understanding why we do one thing or another can help in designing incentives that induce people to cooperate,” the authors of the research pointed out. On the other hand, the fact that the networks are not important has implications, for organizational design, for example. The experiment revealed that people are not going to cooperate more because of being organized in a certain way. In this respect, it can be inferred that we do not have to be concerned with the design of organizational structure, but rather with motivating people individually to cooperate.

Ruling out that network organization influences in the cooperation of people, and having discovered that what is important is reciprocity, that is, cooperating according to cooperation received, will radically change the focus of a significant number of researchers who are developing theories on the emergence of cooperation among individuals.

Source: Science Daily

July 4, 2012

(Medical Xpress) — Researchers at the UCL Institute of Neurology have found that giving the drug rotigotine as a skin patch can improve inattention in some stroke patients.

Hemi-spatial neglect, a severe and common form of inattention that can be caused by brain damage following a stroke, is one of the most debilitating symptoms, frequently preventing patients from living independently. When the right side of the brain has suffered damage, the patient may have little awareness of their left-hand side and have poor memory of objects that they have seen, leaving them inattentive and forgetful. Currently there are few treatment options.

The randomised control trial took 16 patients who had suffered a stroke on the right-hand side of their brain and assessed to see whether giving the drug rotigotine improved their ability to concentrate on their left-hand side. The results showed that even with treatment for just over a week, patients who received the drug performed significantly better on attention tests than when they received the placebo treatment.

Rotigotine acts by stimulating receptors on nerve cells for dopamine, a chemical normally produced within the brain.

Professor Masud Husain who led the study at the Institute of Neurology at UCL says: “Inattention can have a devastating effect on stroke patients and their families. It impacts on all aspects of their lives. If the results of our clinical trial are replicated in further, larger studies, we will have overcome a major hurdle towards providing a new treatment for this important consequence of stroke.

“Milder forms of inattention occur in other brain disorders, across all ages - from ADHD (attention deficit hyperactivity disorder) to Parkinson’s disease. Our findings show that it is possible to alter attention by using a drug that acts at specific receptors in the brain, and therefore have implications for understanding the mechanisms that might cause inattention in conditions other than stroke.”

Provided by University College London

Source: medicalxpress.com

ScienceDaily (July 3, 2012) — University of Granada researchers have developed an artificial cerebellum (a biologically-inspired adaptive microcircuit) that controls a robotic arm with human-like precision. The cerebellum is the part of the human brain that controls the locomotor system and coordinates body movements.

To date, although robot designers have achieved very precise movements, such movements are performed at very high speed, require strong forces and are power consuming. This approach cannot be applied to robots that interact with humans, as a malfunction might be potentially dangerous.

To solve this challenge, University of Granada researchers have implemented a new cerebellar spiking model that adapts to corrections and stores their sensorial effects; in addition, it records motor commands to predict the action or movement to be performed by the robotic arm. This cerebellar model allows the user to articulate a state-of-the-art robotic arm with extraordinary mobility.

Automatic Learning

The developers of the new cerebellar model have obtained a robot that performs automatic learning by extracting the input layer functionalities of the brain cortex. Furthermore, they have developed two control systems that enable accurate and robust control of the robotic arm during object handling.

The synergy between the cerebellum and the automatic control system enables robot’s adaptability to changing conditions i.e. the robot can interact with humans. The biologically-inspired architectures used in this model combine the error training approach with predictive adaptive control.

The designers of this model are Silvia Tolu, Jesús Garrido and Eduardo Ros Vidal, at the University of Granada Department of Computer Architecture and Technology, and the University of Almería researcher Richard Carrillo.

Source: Science Daily

ScienceDaily (July 3, 2012) — When a person injures their knee, it becomes inflamed. When a person has a cold, their throat becomes inflamed. This type of inflammation is the body’s natural and protective response to injury.

Interestingly, there is growing evidence that a similar process happens when a person experiences psychological trauma. Unfortunately, this type of inflammation can be destructive.

Previous studies have linked depression and inflammation, particularly in individuals who have experienced early childhood adversity, but overall, findings have been inconsistent. Researchers Gregory Miller and Steve Cole designed a longitudinal study in an effort to resolve these discrepancies, and their findings are now published in a study in Biological Psychiatry.

They recruited a large group of female adolescents who were healthy, but at high risk for experiencing depression. The volunteers were then followed for 2 ½ years, undergoing interviews and giving blood samples to measure their levels of C-reactive protein and interleukin-6, two types of inflammatory markers. Their exposure to childhood adversity was also assessed.

The researchers found that when individuals who suffered from early childhood adversity became depressed, their depression was accompanied by an inflammatory response. In addition, among subjects with previous adversity, high levels of interleukin-6 forecasted risk of depression six months later. In subjects without childhood adversity, there was no such coupling of depression and inflammation.

Dr. Miller commented on their findings: “What’s important about this study is that it identifies a group of people who are prone to have depression and inflammation at the same time. That group of people experienced major stress in childhood, often related to poverty, having a parent with a severe illness, or lasting separation from family. As a result, these individuals may experience depressions that are especially difficult to treat.”

Another important aspect to their findings is that the inflammatory response among the high-adversity individuals was still detectable six months later, even if their depression had abated, meaning that the inflammation is chronic rather than acute. “Because chronic inflammation is involved in other health problems, like diabetes and heart disease, it also means they have greater-than-average risk for these problems. They, along with their doctors, should keep an eye out for those problems,” added Dr. Miller.

"This study provides important additional support for the notion that inflammation is an important and often under-appreciated factor that compromises resilience after major life stresses. It provides evidence that these inflammatory states persist for long periods of time and have important functional correlates," said Dr. John Krystal, Editor of Biological Psychiatry.

Further research is necessary, to extend the findings beyond female adolescents and particularly in individuals with more severe, long-term depression.. However, findings such as these may eventually help doctors and clinicians better manage depression and medical illness for particularly vulnerable patients.

Source: medicalxpress.com

ScienceDaily (July 3, 2012) — Exposure to childhood maltreatment increases the risk for most psychiatric disorders as well as many negative consequences of these conditions. This new study, by Dr. Gustavo Turecki and colleagues at McGill University, Canada, provides important insight into one of the most extreme outcomes, suicide.

"In this study, we expanded our previous work on the epigenetic regulation of the glucocorticoid receptor gene by investigating the impact of severe early-life adversity on DNA methylation," explained Dr. Turecki. The glucocorticoid receptor is important because it is a brain target for the stress hormone cortisol.

The researchers studied brain tissue from people who had committed suicide, some of whom had a history of childhood maltreatment, and compared that tissue to people who had died from other causes. They found that particular variants of the glucocorticoid receptor were less likely to be present in the limbic system, or emotion circuit, of the brain in people who had committed suicide and were maltreated as children compared to the other two groups..

This study also advances the understanding of how the altered pattern of glucocorticoid receptor regulation developed in the maltreated suicide completers. The authors found that the pattern of methylation of the gene coding for the glucocorticoid receptors was altered in those who completed suicide and who also had a history of abuse. These DNA methylation differences were associated with distinct gene expression patterns.

Since methylation is one way that genes are switched on or off for long periods of time, it appears that childhood adversity can produce long-lasting changes in the regulation of a key stress response system that may be associated with increased risk for suicide.

"Preventing suicide is a critical challenge for psychiatry. This study provides important new information about brain changes that may increase the risk of suicide," said Dr. John Krystal, Editor of Biological Psychiatry. "It is striking that early life maltreatment can produce these long-lasting changes in the control of specific genes in the brain. It is also troubling that the consequences of this process can be so dire. Thus, it is important that we continue to study these epigenetic processes that seem to underlie aspects of the lasting consequences of childhood adversity."

Source: Science Daily

ScienceDaily (July 3, 2012) — searchers from the University of Maryland School of Maryland report promising results from using adult stem cells from bone marrow in mice to help create tissue cells of other organs, such as the heart, brain and pancreas — a scientific step they hope may lead to potential new ways to replace cells lost in diseases such as diabetes, Parkinson’s or Alzheimer’s.

The research in collaboration with the University of Paris Descartes is published online in the June 29, 2012 edition of Comptes Rendus Biologies, a publication of the French Academy of Sciences.

"Finding stem cells capable of restoring function to different damaged organs would be the Holy Grail of tissue engineering," says lead author David Trisler, PhD, assistant professor of neurology at the University of Maryland School of Medicine.

He adds, “This research takes us another step in that process by identifying the potential of these adult bone marrow cells, or a subset of them known as CD34+ bone marrow cells, to be ‘multipotent,’ meaning they could transform and function as the normal cells in several different organs.”

University of Maryland researchers previously developed a special culturing system to collect a select sample of these adult stem cells in bone marrow, which normally makes red and white blood cells and immune cells. In this project, the team followed a widely recognized study model, used to prove the multipotency of embryonic stem cells, to prove that these bone marrow stem cells could make more than just blood cells. The investigators also found that the CD34+ cells had a limited lifespan and did not produce teratomas, tumors that sometimes form with the use of embryonic stem cells and adult stem cells cultivated from other methods that require some genetic manipulation.

"When taken at an early stage, we found that the CD34+ cells exhibited similar multipotent capabilities as embryonic stem cells, which have been shown to be the most flexible and versatile. Because these CD34+ cells already exist in normal bone marrow, they offer a vast source for potential cell replacement therapy, particularly because they come from a person’s own body, eliminating the need to suppress the immune system, which is sometimes required when using adults stem cells derived from other sources," explains Paul Fishman, MD, PhD, professor of neurology at the University of Maryland School of Medicine.

The researchers say that proving the potential of these adult bone marrow stem cells opens new possibilities for scientific exploration, but that more research will be needed to see how this science can be translated to humans.

Source: Science Daily

ScienceDaily (July 3, 2012) — As the United States confronts the growing epidemic of obesity among children and adults, a team of University of Colorado School of Medicine obesity researchers concludes that what the nation needs is a new battle plan — one that replaces the emphasis on widespread food restriction and weight loss with an emphasis on helping people achieve “energy balance” at a healthy body weight.

In a paper published in the July 3 issue of the journal Circulation, James O. Hill, PhD. and colleagues at the Anschutz Health and Wellness Center take on the debate over whether excessive food intake or insufficient physical activity cause obesity, using the lens of energy balance — which combines food intake, energy expended through physical activity and energy (fat) storage — to advance the concept of a “regulated zone,” where the mechanisms by which the body establishes energy balance are managed to overcome the body’s natural defenses towards preserving existing body weight. This is accomplished by strategies that match food and beverage intake to a higher level of energy expenditure than is typical in America today, enabling the biological system that regulates body weight to work more effectively. Additional support for this concept comes from many studies showing that higher levels of physical activity are associated with low weight gain whereas comparatively low levels of activity are linked to high weight gain over time.

"A healthy body weight is best maintained with a higher level of physical activity than is typical today and with an energy intake that matches," explained Hill, professor of pediatrics and medicine and executive director of the Anschutz Health and Wellness Center at the University of Colorado Anschutz Medical Campus and the lead author of the paper. "We are not going to reduce obesity by focusing only on reducing food intake. Without increasing physical activity in the population we are simply promoting unsustainable levels of food restriction. This strategy hasn’t worked so far and it is not likely to work in the future.

As Dr. Hill explains, “What we are really talking about is changing the message from ‘Eat Less, Move More” to ‘Move More, Eat Smarter.’ “

The authors argue that preventing excessive weight gain is a more achievable goal than treating obesity once it is present. Here, the researchers stress that reducing calorie intake by 100 calories a day would prevent weight gain in 90 percent of the adult population and is achievable through small increases in physical activity and small changes in food intake.

People who have a low level of physical activity have trouble achieving energy balance because they must constantly use food restriction to match energy intake to a low level of energy expenditure. Constant food restriction is difficult to maintain long-term and when it cannot be maintained, the result is positive energy balance (when the calories consumed are greater than the calories expended) and an increase in body mass, of which 60 percent to 80 percent is usually body fat. The increasing body mass elevates energy expenditure and helps reestablish energy balance. In fact, the researchers speculate that becoming obese may be the only way to achieve energy balance when living a sedentary lifestyle in a food-abundant environment.

Using an exhaustive review of the energy balance literature as the basis, the researchers also refuted the popular theory that escalating obesity rates can be attributed exclusively to two factors — the change in the American diet and the rise in overall energy intake without a compensatory increase in energy expenditure. Using rough estimates of increases in food intake and decreases in physical activity from 1971 to 2000, the researchers calculated that were it not for the physiological processes that produce energy balance, American adults would have experienced a 30 to 80 fold increase in weight gain during that period, which demonstrates why it is not realistic to attribute obesity solely to caloric intake or physical activity levels. In fact, energy expenditure has dropped dramatically over the past century as our lives now require much less physical activity just to get through the day. The authors argue that this drop in energy expenditure was a necessary prerequisite for the current obesity problem, which necessitates adding a greater level of physical activity back into our modern lives.

"Addressing obesity requires attention to both food intake and physical activity, said co-author John Peters, PhD., assistant director of the Anschutz Health and Wellness Center. "Strategies that focus on either alone will not likely work."

In addition, the researchers conclude that food restriction alone is not effective in reducing obesity, explaining that although caloric restriction produces weight loss, this process triggers hunger and the body’s natural defense to preserve existing body weight, which leads to a lower resting metabolic rate and notable changes in how the body burns calories. As a result, energy requirements after weight loss can be reduced from 170 to 250 calories for a 10 percent weight loss and from 325 to 480 calories for a 20 percent weight loss. These findings provide insight concerning weight loss plateau and the common occurrence of regaining weight after completing a weight loss regimen.

Recognizing that energy balance is a new concept for to the public, the researchers call for educational efforts and new information tools that will teach Americans about energy balance and how food and physical activity choices affect energy balance.

Source: Science Daily