Posts tagged research
Articles and news from the latest research reports.
The zebrafish is a major player in the study of vertebrate biology and human disease. Its transparent, externally fertilized eggs, short reproductive cycle and fast growth mean that its embryonic development can be studied closely while the animal is alive, and the fish is a useful model for studying gene behaviour and function.
Now, researchers led by Stephen Ekker, a molecular biologist at the Mayo Clinic in Rochester, Minnesota, have for the first time made custom changes to parts of the zebrafish (Danio rerio) genome, using artificial enzymes to cut portions of DNA out of targeted positions in a gene sequence, and replace them with synthetic DNA.
Neuroscientists are trying to work out why the brain does so much when it seems to be doing nothing at all.
For volunteers, a brain-scanning experiment can be pretty demanding. Researchers generally ask participants to do something — solve mathematics problems, search a scene for faces or think about their favoured political leaders — while their brains are being imaged.
But over the past few years, some researchers have been adding a bit of down time to their study protocols. While subjects are still lying in the functional magnetic resonance imaging (fMRI) scanners, the researchers ask them to try to empty their minds. The aim is to find out what happens when the brain simply idles. And the answer is: quite a lot.
Improving Memory for Specific Events Can Alleviate Symptoms of Depression
Hear the word “party” and memories of your 8th birthday sleepover or the big bash you attended last New Year’s may come rushing to mind. But it’s exactly these kinds of memories, embedded in a specific place and time, that people with depression have difficulty recalling.
Research has shown that people who suffer from, or are at risk of, depression have difficulty tapping into specific memories from their own past, an impairment that affects their ability to solve problems and leads them to focus on feelings of distress.
In a study forthcoming in Clinical Psychological Science, a new journal of the Association for Psychological Science, psychological scientists Hamid Neshat-Doost of the University of Isfahan, Iran, Laura Jobson of the University of East Anglia, Tim Dalgleish of the Cognition and Brain Sciences Unit, Medical Research Council, Cambridge and colleagues investigated whether a particular training program, Memory Specificity Training, might improve people’s memory for past events and ameliorate their symptoms of depression.
In Iran, the researchers recruited 23 adolescent Afghani refugees who had lost their fathers in the war in Afghanistan and who showed symptoms of depression. Twelve of the adolescents were randomly assigned to participate in the memory training program and 11 were randomly assigned to a control group that received no training.
All of the adolescents completed a memory test in which they saw 18 positive, neutral, and negative words in Persian and were asked to recall a specific memory related to each word. Their responses were categorized as either a specific or a non-specific type of memory. They also completed questionnaires design to measure symptoms of depression and anxiety symptoms.
For five weeks, the adolescents assigned to the training attended a weekly 80-minute group session, in which they learned about different types of memory and memory recall, and practiced recalling specific memories after being given positive, neutral, and negative keywords.
At the end of the five weeks, both the training group and the control group were given the same memory test that they were given at the beginning of the study. And they took the memory test again as part of a follow-up visit two months later.
The adolescents who participated in the training were able to provide more specific memories after the training than those who did not receive intervention. They also showed fewer symptoms of depression than the control group at the two month follow-up. The researchers found that the relationship between participant group (training or control) and their symptoms of depression at follow-up could be accounted for by changes in specific memory recall over time.
These findings are promising because they suggest that a standalone training program that focuses on specific memory recall can actually improve depression symptoms.
Based on the results of this study, Jobson, Dalgleish, and colleagues conclude that, for individuals suffering from depression, “including a brief training component that targets memory recall as an adjunct to cognitive behavioral therapy or prior therapy may have beneficial effects on memory recall and mood.”
Vanderbilt University researchers studying interventions for adolescents and young adults with autism are reporting that there is insufficient evidence to support findings, good or bad, for the therapies currently used.
The researchers systematically screened more than 4,500 studies and reviewed the 32 studies published from January 1980 to December 2011 on therapies for people ages 13 to 30 with autism spectrum disorders. They focused on the outcomes, including harms and adverse effects, of interventions, including medical, behavioral, educational and vocational.
• Some evidence revealed that treatments could improve social skills and educational outcomes such as vocabulary or reading, but the studies were generally small and had limited follow-up.
• Limited evidence supports the use of medical interventions in adolescents and young adults with autism. The most consistent findings were identified for the effects of antipsychotic medications on reducing problem behaviors that tend to occur with autism, such as irritability and aggression. Harms associated with medications included sedation and weight gain.
• Only five articles tested vocational interventions, all of which suggested that certain vocational interventions may be effective for certain individuals, but each study had significant flaws that limited the researchers’ confidence in their conclusions.
A Systematic Review of Vocational Interventions for Young Adults With Autism Spectrum Disorders
The 2007 study by Yale University researchers provided the first evidence that 6- and 10-month-old infants could assess individuals based on their behaviour towards others, showing a preference for those who helped rather than hindered another individual.
Based on a series of experiments, researchers in the Department of Psychology at Otago have shown that the earlier findings may simply be the result of infants’ preferences for interesting and attention grabbing events, rather than an ability to evaluate individuals based on their social interactions with others.
"The paper received a lot of attention when it was first published, including coverage in the New York Times. It has received well over 100 citations since 2007, a phenomenal number over such a short period. The paper was initially brought to our attention by one of the PhD students in our lab. The head of the lab, Professor Harlene Hayne, suggested that a group of us read the paper together and then meet to discuss it. Our original motivation for reading the paper was merely interest. Obviously, the idea that morality is innate is extremely interesting and, if true, would raise questions about which components of our moral system are innate and also have implications for the wider issue of the roles that nature and nurture play in development," says Dr Scarf.
The Otago study was recently published in PLoS One
New University of Otago research into two sex hormones released by the testes of male fetuses and boys may help solve the enduring mystery of why autism is much more common in boys than girls.
The researchers studied blood samples from 82 boys with ASD and 16 control boys, all aged between 4.4 to 8.9 years. Measuring the levels of the two hormones, the researchers found that these were highly variable from boy to boy, but no different on average between the two groups of boys.
Professor McLennan says the findings indicate that male hormones are important for autism, but not because autistic boys have abnormal levels.
While it has been previously suggested that exposure in the womb to excessive levels of testosterone might be creating an ‘extreme male brain’, this does not explain why some females have autism, or why males with autism do not exhibit an extreme male physical form.
"Our data suggest that the still-elusive primary initiating cause of ASD is common to both males and females, with the condition being more frequent in males because normal levels of male hormones exacerbates the pathology,” he says.
The researchers say that their hypothesis now needs further testing through longitudinal studies of at-risk male babies to determine whether their levels of AMH and InhB early in development can predict the breadth of autistic traits later in life.
(Image credit: ©iStockphoto.com/ktaylorg)
So many scientific studies are making incorrect claims that a new service has sprung up to fact-check reported findings by repeating the experiments.
A year-old Palo Alto, California, company, Science Exchange, announced on Tuesday its “Reproducibility Initiative,” aimed at improving the trustworthiness of published papers. Scientists who want to validate their findings will be able to apply to the initiative, which will choose a lab to redo the study and determine whether the results match.
The project sprang from the growing realization that the scientific literature - from social psychology to basic cancer biology - is riddled with false findings and erroneous conclusions, raising questions about whether such studies can be trusted. Not only are erroneous studies a waste of money, often taxpayers’, but they also can cause companies to misspend time and resources as they try to invent drugs based on false discoveries.
Last year, Bayer Healthcare reported that its scientists could not reproduce some 75 percent of published findings in cardiovascular disease, cancer and women’s health. In March, Lee Ellis of M.D. Anderson Cancer Center and C. Glenn Begley, the former head of global cancer research at Amgen, reported that when the company’s scientists tried to replicate 53 prominent studies in basic cancer biology, hoping to build on them for drug discovery, they were able to confirm the results of only six.
The new initiative, said Begley, senior vice president of privately held biotechnology company TetraLogic, “recognizes that the problem of non-reproducibility exists and is taking the right steps to address it.”
The initiative’s 10-member board of prominent scientists will match investigators with a lab qualified to test their results, said Elizabeth Iorns, Science Exchange’s co-founder and chief executive officer. The original lab would pay the second for its work. How much depends on the experiment’s complexity and the cost of study materials, but should not exceed 20 percent of the original research study’s costs. Iorns hopes government and private funding agencies will eventually fund replication to improve the integrity of scientific literature.
These days, 3D printing is being used to mock up far more complex systems, says Arthur Olson, who founded the molecular graphics lab at the Scripps Research Institute in La Jolla, California, 30 years ago. These include molecular environments made up of thousands of interacting proteins, which would be onerous-to-impossible to make any other way. With 3D printers, Olson says, “anybody can make a custom model”. But not everybody does: many researchers lack easy access to a printer, aren’t aware of the option or can’t afford the printouts (which can cost $100 or more).
DARPA and NIH to fund ‘human body on a chip’ research
Researchers in the Department of Biological Engineering at MIT plan to develop a technology platform that will mimic human physiological systems in the laboratory, using an array of integrated, interchangeable engineered human tissue constructs, with $32 million funding over the next five years from the Defense Advanced Research Projects Agency (DARPA) and the National Institutes of Health (NIH).
The BIO-MIMETICS program will combine technologies developed at MIT, Draper Laboratory, MatTek and Zyoxel to create a versatile microfluidic platform that can incorporate up to 10 individual engineered human microphysiological organ system modules in an interacting circuit. The modules will be designed to mimic the functions of specific organ systems representing a broad spectrum of human tissues, including the circulatory, endocrine, gastrointestinal, immune, integumentary, musculoskeletal, nervous, reproductive, respiratory and urinary systems.
The goal of the program is to create a versatile platform capable of accurately predicting drug and vaccine efficacy, toxicity, and pharmacokinetics in preclinical testing. The BIO-MIMETICS team anticipates that the platform will be suitable for use in regulatory review, amenable to rapid translation to the biopharmaceutical research community, and adaptable for integration of future technologies (such as advances in stem cell technologies and personalized medicine).
Research shows gene defect’s role in autism-like behavior
August 10, 2012
Scientists affiliated with the UC Davis MIND Institute have discovered how a defective gene causes brain changes that lead to the atypical social behavior characteristic of autism. The research offers a potential target for drugs to treat the condition.
Earlier research already has shown that the gene is defective in children with autism, but its effect on neurons in the brain was not known. The new studies in mice show that abnormal action of just this one gene disrupted energy use in neurons. The harmful changes were coupled with antisocial and prolonged repetitive behavior — traits found in autism.
The research is published online today in the scientific journal PLoS ONE.
"A number of genes and environmental factors have been shown to be involved in autism, but this study points to a mechanism — how one gene defect may trigger this type of neurological behavior," said study senior author Cecilia Giulivi, professor of molecular biosciences in the UC Davis School of Veterinary Medicine and a researcher affiliated with the UC Davis MIND Institute.
"Once you understand the mechanism, that opens the way for developing drugs to treat the condition," she said.
The defective gene appears to disrupt neurons’ use of energy, Giulivi said, the critical process that relies on the cell’s molecular energy factories called mitochondria.
In the research, a gene called pten was tweaked in the mice so that neurons lacked the normal amount of pten’s protein. The scientists detected malfunctioning mitochondria in the mice as early as 4 to 6 weeks after birth.
By 20 to 29 weeks, DNA damage in the mitochondria and disruption of their function had increased dramatically. At this time the mice began to avoid contact with their litter mates and engage in repetitive grooming behavior. Mice without the single gene change exhibited neither the mitochondria malfunctions nor the behavioral problems.
The antisocial behavior was most pronounced in the mice at an age comparable in humans to the early teenage years, when schizophrenia and other behavioral disorders become most apparent, Giulivi said.
The research showed that, when defective, pten’s protein interacts with the protein of a second gene known as p53 to dampen energy production in neurons. This severe stress leads to a spike in harmful mitochondrial DNA changes and abnormal levels of energy production in the cerebellum and hippocampus — brain regions critical for social behavior and cognition.
Pten mutations previously have been linked to Alzheimer’s disease as well as a spectrum of autism disorders. The new research shows that when pten protein was insufficient, its interaction with p53 triggered deficiencies and defects in other proteins that also have been found in patients with learning disabilities including autism.
Source: UCDavis