Posts tagged science
Articles and news from the latest research reports.
A*STAR scientists have identified a biomarker of the most lethal form of brain tumours in adults − glioblastoma multiforme. The scientists found that by targeting this biomarker and depleting it with a potential drug, they were able to prevent the progression and relapse of the brain tumour.
Researchers have discovered two gene variants that raise the risk of the pediatric cancer neuroblastoma. Using automated technology to perform genome-wide association studies on DNA from thousands of subjects, the study broadens understanding of how gene changes may make a child susceptible to this early childhood cancer, as well as causing a tumor to progress.
“We discovered common variants in the HACE1 and LIN28B genes that increase the risk of developing neuroblastoma. For LIN28B, these variants also appear to contribute to the tumor’s progression once it forms,” said first author Sharon J. Diskin, PhD, a pediatric cancer researcher at The Children’s Hospital of Philadelphia. “HACE1 and LIN28B are both known cancer-related genes, but this is the first study to link them to neuroblastoma.”
Diskin and colleagues, including senior author John M. Maris, MD, director of the Center for Childhood Cancer Research at Children’s Hospital, published the study online Sept. 2 in Nature Genetics.
Spinal cord injury victims may be able to look forward to life beyond a wheelchair via a robotic leg prosthesis controlled by brain waves. Individuals with paraplegia due to spinal cord injury who are wheelchair-bound face serious health problems, or in medical terminology, comorbidities, such as metabolic derangement, heart disease, osteoporosis, and pressure ulcers. New research efforts are being directed toward restoring brain-controlled ambulation for those who suffer from spinal cord injuries.
Every day, we face thousands of decisions both major and minor — from whether to eat that decadent chocolate cupcake to when to pursue a new romantic relationship or to change careers. How does the brain decide? A new study suggests that it relies on two separate networks to do so: one that determines the overall value — the risk versus reward — of individual choices and another that guides how you ultimately behave.
Reduced Brain Connections Seen in People With Generalized Anxiety Disorder
A new University of Wisconsin-Madison imaging study shows the brains of people with generalized anxiety disorder (GAD) have weaker connections between a brain structure that controls emotional response and the amygdala, which suggests the brain’s “panic button” may stay on due to lack of regulation.
Anxiety disorders are the most common class of mental disorders and GAD, which is characterized by excessive, uncontrollable worry, affects nearly 6 percent of the population.
Lead author Dr. Jack Nitschke, associate professor of psychiatry in the UW School of Medicine and Public Health, says the findings support the theory that reduced communications between parts of the brain explains the intense anxiety felt by people with GAD.
In this case, two types of scans showed the amygdala, which alerts us to threat in our surroundings and initiates the “fight-or-flight” response, seems to have weaker “white matter” connections to the prefrontal and anterior cingulate cortex (ACC), the center of emotional regulation.
The researchers did two types of imaging - diffusion tensor imaging (DTI) and functional magnetic resonance (fMRI) - on the brains of 49 GAD patients and 39 healthy volunteers. Compared with the healthy volunteers, the imaging showed the brains of people with GAD had reduced connections between the prefrontal and anterior cingulate cortex and the amygdala via the uncinate fasciculus, a primary “white matter” tract that connects these brain regions. This reduced connectivity was not found in other white matter tracts elsewhere in their brains.
"We know that in the brain, if you use a circuit you build it up, the way you build muscle by exercise,” says Nitschke, a clinical psychologist who treats patients with anxiety disorders and does research at the UW-Madison’s Waisman Center.
Nitschke says that researchers wonder if this weak connection results in the intense anticipatory anxiety and worry that is the hallmark of GAD, because the ACC is unable to tell the amygdala to “chill out.” It also suggests that behavioral therapy that teaches patients to consciously exercise this emotional regulation works to reduce anxiety by strengthening the connection.
"It’s possible that this is exactly what we’re doing when we teach patients to regulate their reactions to the negative events that come up in everyone’s lives,” Nitschke says. "We can help build people’s tolerance to uncontrollable future events by teaching them to regulate their emotions to the uncertainty that surrounds those events.
(Source: news.wisc.edu)
Stem cells bring back feeling for paralysed patients
03 September 2012 by Andy Coghlan
For the first time, people with broken spines have recovered feeling in previously paralysed areas after receiving injections of neural stem cells.
(Image: Medical Images/Getty Images)
Three people with paralysis received injections of 20 million neural stem cells directly into the injured region of their spinal cord. The cells, acquired from donated fetal brain tissue, were injected between four and eight months after the injuries happened. The patients also received a temporary course of immunosuppressive drugs to limit rejection of the cells.
None of the three felt any sensation below their nipples before the treatment. Six months after therapy, two of them had sensations of touch and heat between their chest and belly button. The third patient has not seen any change.
"The fact we’ve seen responses to light touch, heat and electrical impulses so far down in two of the patients is very unexpected," says Stephen Huhn of StemCells, the company in Newark, California, developing and testing the treatment. "They’re really close to normal in those areas now in their sensitivity," he adds.
"We are very intrigued to see that patients have gained considerable sensory function," says Armin Curt of Balgrist University Hospital in Zurich, Switzerland, where the patients were treated, and principal investigator in the trial.
The data are preliminary, but “these sensory changes suggest that the cells may be positively impacting recovery”, says Curt, who presented the results today in London at the annual meeting of the International Spinal Cord Society.
Combat Stress in Afghanistan Could Alter Soldiers’ Long-term Neural Makeup
Some soldiers who serve in Afghanistan or other war-torn countries return home with visible injuries: concussions, broken bones or amputated limbs. Many others, though, suffer from injuries we can’t visibly see. The daily strain of being exposed to armed combat, enemy fire and unpredictable explosions can lead to a range of behavioral symptoms, including fatigue, slower reaction times and a difficulty in connecting to one’s immediate surroundings.
A new study of soldiers returning home from Afghanistan, published today online in the Proceedings of the National Academy of Sciences, hints at the underlying cause for these behavioral changes. Researchers from the Netherlands and elsewhere used neurological exams and MRI scanning techniques to examine 33 soldiers before and after a four-month deployment in NATO’s International Security Assistance Force, and compared them to a control group of 26 soldiers who were never deployed.
The results were sobering—and indicate that a relatively short period of combat stress can alter an individual’s neurological circuitry for a long time.
You already know it’s hard to balance your checkbook while simultaneously reflecting on your past. Now, investigators at the Stanford University School of Medicine — having done the equivalent of wire-tapping a hard-to-reach region of the brain — can tell us how this impasse arises.
The researchers showed that groups of nerve cells in a structure called the posterior medial cortex, or PMC, are strongly activated during a recall task such as trying to remember whether you had coffee yesterday, but just as strongly suppressed when you’re engaged in solving a math problem.
The PMC, situated roughly where the brain’s two hemispheres meet, is of great interest to neuroscientists because of its central role in introspective activities.
“This brain region is famously well-connected with many other regions that are important for higher cognitive functions,” said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of Stanford’s Human Intracranial Cognitive Electrophysiology Program. “But it’s very hard to reach. It’s so deep in the brain that the most commonly used electrophysiological methods can’t access it.”
Ιn a study published online Sept. 3 in Proceedings of the National Academy of Sciences, Parvizi and his Stanford colleagues found a way to directly and sensitively record the output from this ordinarily anatomically inaccessible site in human subjects. By doing so, the researchers learned that particular clusters of nerve cells in the PMC that are most active when you are recalling details of your own past are strongly suppressed when you are performing mathematical calculations.
Even in normal range, high blood sugar linked to brain shrinkage
September 3, 2012
People whose blood sugar is on the high end of the normal range may be at greater risk of brain shrinkage that occurs with aging and diseases such as dementia, according to new research published in the September 4, 2012, print issue of Neurology, the medical journal of the American Academy of Neurology.
"Numerous studies have shown a link between type 2 diabetes and brain shrinkage and dementia, but we haven’t known much about whether people with blood sugar on the high end of normal experience these same effects," said study author Nicolas Cherbuin, PhD, with Australian National University in Canberra.
The study involved 249 people age 60 to 64 who had blood sugar in the normal range as defined by the World Health Organization. The participants had brain scans at the start of the study and again an average of four years later.
Those with higher fasting blood sugar levels within the normal range and below 6.1 mmol/l (or 110 mg/dL) were more likely to have a loss of brain volume in the areas of the hippocampus and the amygdala, areas that are involved in memory and cognitive skills, than those with lower blood sugar levels. A fasting blood sugar level of 10.0 mmol/l (180 mg/dL) or higher was defined as diabetes and a level of 6.1 mmol/l (110 mg/dL) was considered impaired, or prediabetes.
After controlling for age, high blood pressure, smoking, alcohol use and other factors, the researchers found that blood sugar on the high end of normal accounted for six to 10 percent of the brain shrinkage.
"These findings suggest that even for people who do not have diabetes, blood sugar levels could have an impact on brain health," Cherbuin said. "More research is needed, but these findings may lead us to re-evaluate the concept of normal blood sugar levels and the definition of diabetes."
Source: medicalxpress.com
Obesity and Metabolic Syndrome Associated With Impaired Brain Function in Adolescents
ScienceDaily (Sep. 3, 2012) — A new study by researchers at NYU School of Medicine reveals for the first time that metabolic syndrome (MetS) is associated with cognitive and brain impairments in adolescents and calls for pediatricians to take this into account when considering the early treatment of childhood obesity.
The study, funded by the National Institutes of Health under award number DK083537, and in part by award number 1ULIRR029892, from the National Center for Research Resources, appears online September 3 in Pediatrics.
As childhood obesity has increased in the U.S., so has the prevalence of metabolic syndrome — a constellation of three or more of five defined health problems, including abdominal obesity, low HDL (good cholesterol), high triglycerides, high blood pressure and pre-diabetic insulin resistance. Lead investigator Antonio Convit, MD, professor of psychiatry and medicine at NYU School of Medicine and a member of the Nathan Kline Research Institute, and colleagues have shown previously that metabolic syndrome has been linked to neurocognitive impairments in adults, but this association was generally thought to be a long-term effect of poor metabolism. Now, the research team has revealed even worse brain impairments in adolescents with metabolic syndrome, a group absent of clinically-manifest vascular disease and likely shorter duration of poor metabolism.
"The prevalence of MetS parallels the rise in childhood obesity," Dr. Convit said. "There are huge numbers of people out there who have problems with their weight. If those problems persist long enough, they will lead to the development of MetS and diabetes. As yet, there has been very little information available about what happens to the brain in the setting of obesity and MetS and before diabetes onset in children."