Posts tagged disorder
Posts tagged disorder
A new UCLA study pinpoints uniquely human patterns of gene activity in the brain that could shed light on how we evolved differently than our closest relative. Published Aug. 22 in the advance online edition of Neuron, these genes’ identification could improve understanding of human brain diseases like autism and schizophrenia, as well as learning disorders and addictions.
(Image by Michael Nichols)
23 JUILLET 2012
Children with trisomy 13 or 18, who are for the most part severely disabled and have a very short life expectancy, and their families lead a life that is happy and rewarding overall, contrary to the usually gloomy predictions made by the medical community at the time of diagnosis, according to a study of parents who are members of support groups published today inPediatrics. The study was conducted by Dr. Annie Janvier of the Sainte-Justine University Hospital Center and the University of Montreal with the special collaboration of the mother of a child who died from trisomy 13, Barbara Farlow, Eng, MSc as the second author.
Source : Wikimedia Commons
The study interviewed 332 parents who live or have lived with 272 children with trisomy 13 or 18. It turns out that their experience diverges substantially from what healthcare providers said it would be, according to which their child would have been “incompatible with life” (87 %), would have been “a vegetable” (50 %), would have led “a life of suffering” (57 %) or would have “ruin their family or life as a couple” (23 %).
It should be noted that trisomies 13 and 18 are rare chromosome disorders that are most often diagnosed before birth and sometimes after. Children who have received these diagnoses generally do not survive beyond their first year of life, while some who do have severe disabilities and a short life. When trisomy 13 or 18 is diagnosed before birth, many parents decide to interrupt the pregnancy, whereas others choose to carry it to term and in such cases miscarriages are common.
As children with trisomies 13 or 18 generally receive palliative care at birth, some parents who opt to continue the pregnancy or desire life-prolonging interventions for their child encounter the prejudices of the medical system. In this regard, the parents interviewed in the study consider that caregivers often view their child in terms of a diagnosis (“a T13”, “a lethal trisomy”) rather than a unique baby.
“Our study points out that physicians and parents can have different views of what constitutes quality of life,” states Dr. Annie Janvier, a neonatologist and co-founder of the Master’s program in Pediatric Clinical Ethics at the University of Montreal. In fact, over 97% of the parents interviewed considered that their child was happy and its presence enriched the life of their family and their life as a couple regardless of longevity. “In the medical literature on all handicaps, disabled patients – or their families – rated their quality of life as being higher than caregivers did,” adds Dr. Annie Janvier.
Parents who receive a new diagnosis of trisomy 13 and 18 and join a parental support group often acquire a more positive image of these diagnoses than the predictions made by the medical profession. In fact, according to the parents interviewed, belonging to a support group helped them view their experience positively. “Our research reveals that some parents who chose a path to accept and to love a disabled child with a short life expectancy have experienced happiness and enrichment. My hope is that this knowledge improves the ability of physicians to understand, communicate and make decisions with these parents,” concludes Barbara Farlow.
Given the rarity of trisomy 13 or 18 cases (one case out of approximately every 10,500 births), the parents were recruited through online support groups that parents often join after receiving the physicians’ diagnosis. Dr. Annie Janvier and Barbara Farlow sometimes give joint talks on the subject of trisomies 13 and 18.
Source: Université de Montréal
July 23, 2012
Ever wonder how the human brain, which is constantly bombarded with millions of pieces of visual information, can filter out what’s unimportant and focus on what’s most useful?
The process is known as selective attention and scientists have long debated how it works. But now, researchers at Wake Forest Baptist Medical Center have discovered an important clue. Evidence from an animal study, published in the July 22 online edition of the journal Nature Neuroscience, shows that the prefrontal cortex is involved in a previously unknown way.
Two types of attention are utilized in the selective attention process – bottom up and top down. Bottom-up attention is automatically guided to images that stand out from a background by virtue of color, shape or motion, such as a billboard on a highway. Top-down attention occurs when one’s focus is consciously shifted to look for a known target in a visual scene, as when searching for a relative in a crowd.
Traditionally, scientists have believed that separate areas of the brain controlled these two processes, with bottom-up attention occurring in the posterior parietal cortex and top-down attention occurring in the prefrontal cortex.
"Our findings provide insights on the neural mechanisms behind the guidance of attention," said Christos Constantinidis, Ph.D., associate professor of neurobiology and anatomy at Wake Forest Baptist and senior author of the study. "This has implications for conditions such as attention deficit hyperactivity disorder (ADHD), which affects millions of people worldwide. People with ADHD have difficulty filtering information and focusing attention. Our findings suggest that both the ability to focus attention intentionally and shifting attention to eye-catching but sometimes unimportant stimuli depend on the prefrontal cortex."
In the Wake Forest Baptist study, two monkeys were trained to detect images on a computer screen while activity in both areas of the brain was recorded. The visual display was designed to let one image “pop out” due to its color difference from the background, such as a red circle surrounded by green. To trigger bottom-up attention, neither the identity nor the location of the pop-out image could be predicted before it appeared. The monkeys indicated that they detected the pop-out image by pushing a lever.
The neural activity associated with identifying the pop-out images occurred in the prefrontal cortex at the same time as in the posterior parietal cortex. This unexpected finding indicates early involvement of the prefrontal cortex in bottom-up attention, in addition to its known role in top-down attention, and provides new insights into the neural mechanisms of attention.
"We hope that our findings will guide future work targeting attention deficits," Constantinidis said.
Provided by Wake Forest University Baptist Medical Center
July 19, 2012 By Emily Martinez
(Medical Xpress) — UT Dallas researchers recently demonstrated how nerve stimulation paired with specific experiences, such as movements or sounds, can reorganize the brain. This technology could lead to new treatments for stroke, tinnitus, autism and other disorders.
Dr. Michael Kilgard helped lead a team that paired vagus nerve stimulation with physical movement to improve brain function.
In a related paper, UT Dallas neuroscientists showed that they could alter the speed at which the brain works in laboratory animals by pairing stimulation of the vagus nerve with fast or slow sounds.
A team led by Dr. Robert Rennaker and Dr. Michael Kilgard looked at whether repeatedly pairing vagus nerve stimulation with a specific movement would change neural activity within the laboratory rats’ primary motor cortex. To test the hypothesis, they paired the vagus nerve stimulation with movements of the forelimb in two groups of rats. The results were published in a recent issue of Cerebral Cortex.
After five days of stimulation and movement pairing, the researchers examined the brain activity in response to the stimulation. The rats who received the training along with the stimulation displayed large changes in the organization of the brain’s movement control system. The animals receiving identical motor training without stimulation pairing did not exhibit any brain changes, or plasticity.
People who suffer strokes or brain trauma often undergo rehabilitation that includes repeated movement of the affected limb in an effort to regain motor skills. It is believed that repeated use of the affected limb causes reorganization of the brain essential to recovery. The recent study suggests that pairing vagus nerve stimulation with standard therapy may result in more rapid and extensive reorganization of the brain, offering the potential for speeding and improving recovery following stroke, said Rennaker, associate professor in The University of Texas at Dallas’ School of Behavioral and Brain Sciences.
“Our goal is to use the brain’s natural neuromodulatory systems to enhance the effectiveness of standard therapies,” Rennaker said. “Our studies in sensory and motor cortex suggest that the technique has the potential to enhance treatments for neurological conditions ranging from chronic pain to motor disorders. Future studies will investigate its effectiveness in treating cognitive impairments.”
ScienceDaily (July 18, 2012) — Researchers at Oregon Health & Science University School of Dentistry have discovered that TDP-43, a protein strongly linked to ALS (amyotrophic lateral sclerosis) and other neurodegenerative diseases, appears to activate a variety of different molecular pathways when genetically manipulated. The findings have implications for understanding and possibly treating ALS and neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
ALS affects two in 100,000 adults in the United States annually and the prognosis for patients is grim.The new discovery is published online in G3: Genes, Genomes, Genetics (and the July 2012 print issue of G3).
Using a fruit fly model, the OHSU team genetically increased or eliminated TDP-43 to study its effect on the central nervous system. By using massively parallel sequencing methods to profile the expression of genes in the central nervous system, the team found that the loss of TDP-43 results in widespread gene activation and altered splicing, much of which is reversed by rescue of TDP-43 expression. Although previous studies have implicated both absence and over expression of TDP-43 in ALS, the OHSU study showed little overlap in the gene expression between these two manipulations, suggesting that the bulk of the genes affected are different.
"Our data suggest that TDP-43 plays a role in synaptic transmission, synaptic release and endocytosis," said Dennis Hazelett, Ph.D., lead author of the study. "We also uncovered a potential novel regulation of several pathways, many targets of which appear to be conserved."
Source: Science Daily
July 18, 2012
Drugs used to treat Attention Deficit Hyperactivity Disorder (ADHD) do not appear to have long-term effects on the brain, according to new animal research from Wake Forest Baptist Medical Center.
As many as five to seven percent of elementary school children are diagnosed with ADHD, a behavioral disorder that causes problems with inattentiveness, over-activity, impulsivity, or a combination of these traits. Many of these children are treated with psychostimulant drugs, and while doctors and scientists know a lot about how these drugs work and their effectiveness, little is known about their long-term effects.
Linda Porrino, Ph.D., professor and chair of the Department of Physiology and Pharmacology, along with fellow professor Michael A. Nader, Ph.D., both of Wake Forest Baptist, and colleagues conducted an animal study to determine what the long-lasting effects may be. Their findings were surprising, said Porrino. “We know that the drugs used to treat ADHD are very effective, but there have always been concerns about the long-lasting effects of these drugs,” Porrino said.
"We didn’t know whether taking these drugs over a long period could harm brain development in some way or possibly lead to abuse of drugs later in adolescence."
Findings from the Wake Forest Baptist research are published online this month in the journal Neuropsychopharmacology.
The researchers studied 16 juvenile non-human primates, whose ages were equivalent to 6-to 10-year-old humans. Eight animals were in the control group that did not receive any drug treatment and the other eight were treated with a therapeutic-level dose of an extended-release form of Ritalin, or methylphenidate (MPH), for over a year, which is equivalent to about four years in children. Imaging of the animals’ brains, both before and after the study, was conducted on both groups to measure brain chemistry and structure. The researchers also looked at developmental milestones to address concerns that ADHD drugs adversely affect physical growth.
Once the MPH treatment and imaging studies were concluded, the animals were given the opportunity to self administer cocaine over several months. Nader measured their propensity to acquire the drug and looked at how rapidly and in what amounts, to provide an index of vulnerability to substance abuse in adolescence. As reported in the research paper, they found no differences between groups – monkeys treated with Ritalin during adolescence were not more vulnerable to later drug use than the control animals.
"After one year of drug therapy, we found no long-lasting effects on the neurochemistry of the brain, no changes in the structure of the developing brain. There was also no increase in the susceptibility for drug abuse later in adolescence," Porrino said. "We were very careful to give the drugs in the same doses that would be given to children. That’s one of the great advantages of our study is that it’s directly translatable to children."
Porrino said non-human primates provide exceptional models for developmental research because they undergo relatively long childhood and adolescent periods marked by hormonal and physiological maturation much like humans.
"Our study showed that long-term therapeutic use of drugs to treat ADHD does not cause long-term negative effects on the developing brain, and importantly, it doesn’t put children at risk for substance abuse later in adolescence," she said.
One of the exciting things about this research, Porrino said, is that a “sister” study was conducted simultaneously at John Hopkins with slightly older aged animals and different drugs and their findings were similar. “We feel very confident of the results because we have replicated each other’s studies within the same time frame and gotten similar results,” she said. “We think that’s pretty powerful and reassuring.”
Provided by Wake Forest University Baptist Medical Center
July 16, 2012
For more than 20 years, doctors have been using cells from blood that remains in the placenta and umbilical cord after childbirth to treat a variety of illnesses, from cancer and immune disorders to blood and metabolic diseases.
This microscope image shows a colony of neurons derived from cord-blood cells using stem cell reprogramming technology. The green and red glow indicates that the cells are producing protein makers found in neurons, evidence that the cord-blood cells did in fact morph into neurons. The blue glow marks the nuclei of the neurons. Credit: Image: Courtesy of Alessandra Giorgetti
Now, scientists at the Salk Institute for Biological Studies have found a new way-using a single protein, known as a transcription factor-to convert cord blood (CB) cells into neuron-like cells that may prove valuable for the treatment of a wide range of neurological conditions, including stroke, traumatic brain injury and spinal cord injury.
The researchers demonstrated that these CB cells, which come from the mesoderm, the middle layer of embryonic germ cells, can be switched to ectodermal cells, outer layer cells from which brain, spinal and nerve cells arise. “This study shows for the first time the direct conversion of a pure population of human cord blood cells into cells of neuronal lineage by the forced expression of a single transcription factor,” says Juan Carlos Izpisua Belmonte, a professor in Salk’s Gene Expression Laboratory, who led the research team. The study, a collaboration with Fred H. Gage, a professor in Salk’s Laboratory of Genetics, and his team, was published on July 16 in the Proceedings of the National Academy of Sciences.
"Unlike previous studies, where multiple transcription factors were necessary to convert skin cells into neurons, our method requires only one transcription factor to convert CB cells into functional neurons," says Gage.
The Salk researchers used a retrovirus to introduce Sox2, a transcription factor that acts as a switch in neuronal development, into CB cells. After culturing them in the laboratory, they discovered colonies of cells expressing neuronal markers. Using a variety of tests, they determined that the new cells, called induced neuronal-like cells (iNC), could transmit electrical impulses, signaling that the cells were mature and functional neurons. Additionally, they transferred the Sox2-infused CB cells to a mouse brain and found that they integrated into the existing mouse neuronal network and were capable of transmitting electrical signals like mature functional neurons.
"We also show that the CB-derived neuronal cells can be expanded under certain conditions and still retain the ability to differentiate into more mature neurons both in the lab and in a mouse brain," says Mo Li, a scientist in Belmonte’s lab and a co-first author on the paper with Alessandra Giorgetti, of the Center for Regenerative Medicine, in Barcelona, and Carol Marchetto of Gage’s lab. "Although the cells we developed were not for a specific lineage-for example, motor neurons or mid-brain neurons-we hope to generate clinically relevant neuronal subtypes in the future."
Importantly, says Marchetto, “We could use these cells in the future for modeling neurological diseases such as autism, schizophrenia, Parkinson’s or Alzheimer’s disease.”
Cord blood cells, says Giorgetti, offer a number of advantages over other types of stem cells. First, they are not embryonic stem cells and thus they are not controversial. They are more plastic, or flexible, than adult stem cells from sources like bone marrow, which may make them easier to convert into specific cell lineages. The collection of CB cells is safe and painless and poses no risk to the donor, and they can be stored in blood banks for later use.
"If our protocol is developed into a clinical application, it could aid in future cell-replacement therapies," says Li. "You could search all the cord blood banks in the country to look for a suitable match."
Provided by Salk Institute
March 20, 2012
A personality profile marked by overly gregarious yet anxious behavior is rooted in abnormal development of a circuit hub buried deep in the front center of the brain, say scientists at the National Institutes of Health. They used three different types of brain imaging to pinpoint the suspect brain area in people with Williams syndrome, a rare genetic disorder characterized by these behaviors. Matching the scans to scores on a personality rating scale revealed that the more an individual with Williams syndrome showed these personality/temperament traits, the more abnormalities there were in the brain structure, called the insula.
The severity of abnormalities in insula (red structure near bottom of brain), gray matter volume (left) and brain activity (right) predicted the extent of aberrant personality traits in Williams syndrome patients — as reflected in their scores (red dots) on personality rating scales (WSPP). Credit: Karen Berman, M.D., NIMH Clinical Brain Disorders Branch
"Scans of the brain’s tissue composition, wiring, and activity produced converging evidence of genetically-caused abnormalities in the structure and function of the front part of the insula and in its connectivity to other brain areas in the circuit," explained Karen Berman, M.D., of the NIH’s National Institute of Mental Health (NIMH).
Berman, Drs. Mbemda Jabbi, Shane Kippenham, and colleagues, report on their imaging study in Williams syndrome online in the journal Proceedings of the National Academy of Sciences.
"This line of research offers insight into how genes help to shape brain circuitry that regulates complex behaviors – such as the way a person responds to others – and thus holds promise for unraveling brain mechanisms in other disorders of social behavior," said NIMH Director Thomas R. Insel, M.D.
Long distance connections, white matter, between the insula and other parts of the brain are aberrant in Williams syndrome. Neuronal fibers of normal controls (left) extend further than those of Williams syndrome patients (right). Picture shows diffusion tensor imaging data from each patient superimposed on anatomical MRI of the median patient. Credit: Karen Berman, M.D., NIMH Clinical Brain Disorders Branch
ScienceDaily (Feb. 23, 2012) — After we sense a threat, our brain center responsible for responding goes into gear, setting off a chain of biochemical reactions leading to the release of cortisol from the adrenal glands.
Dr. Gil Levkowitz and his team in the Molecular Cell Biology Department have now revealed a new kind of ON-OFF switch in the brain for regulating the production of a main biochemical signal from the brain that stimulates cortisol release in the body. This finding, which was recently published in Neuron, may be relevant to research into a number of stress-related neurological disorders.
This signal is corticotropin releasing hormone (CRH). CRH is manufactured and stored in special neurons in the hypothalamus. Within this small brain region the danger is sensed, the information processed and the orders to go into stress-response mode are sent out. As soon as the CRH-containing neurons have depleted their supply of the hormone, they are already receiving the directive to produce more.
The research — on zebrafish — was performed in Levkowitz’s lab and spearheaded by Dr. Liat Amir-Zilberstein together with Drs. Janna Blechman, Adriana Reuveny and Natalia Borodovsky and Maayan Tahor. The team found that a protein called Otp is involved in several stages of CRH production. As well as directly activating the genes encoding CRH, it also regulates the production of two different receptors on the neurons’ surface for receiving and relaying CRH production signals — in effect, ON and OFF switches.
The team found that both receptors are encoded in a single gene. To get two receptors for the price of one, Otp regulates a gene-editing process known as alternative splicing, in which some of the elements in the sequence encoded in a gene can be “cut and pasted” to make slightly different “sentences.” In this case, it generates two variants of a receptor called PAC1: The short version produces the ON receptor; the long version, containing an extra sequence, encodes the OFF receptor. The researchers found that as the threat passed and the supply of CRH was replenished, the ratio between the two types of PAC1 receptor on the neurons’ surface gradually changed from more ON to mostly OFF. In collaboration with Drs Laure Bally-Cuif and William Norton of the Institute of Neurobiology Alfred Fessard at the Centre National de la Recherche Scientifique (CNRS) in France, the researchers showed that blocking the production of the long receptor variant causes an anxiety-like behavior in zebrafish.
Together with Drs. Alon Chen and Yehezkel Sztainberg of the Neurobiology Department, Levkowitz’s team found the same alternatively-spliced switch in mice. This conservation of the mechanism through the evolution of fish and mice implies that a similar means of turning CRH production on and off exists in the human brain.
Faulty switching mechanisms may play a role in a number of stress-related disorders. The action of the PAC1 receptor has recently been implicated in post-traumatic stress disorder, as well as in schizophrenia and depression. Malfunctions in alternative splicing have also been associated with epilepsy, mental retardation, bipolar disorder and autism.
Source: Science Daily
If you are looking for a particular object — say a yellow pencil — on a cluttered desk, how does your brain work to visually locate it?
For the first time, a team led by Carnegie Mellon University neuroscientists has identified how different neural regions communicate to determine what to visually pay attention to and what to ignore. This finding is a major discovery for visual cognition and will guide future research into visual and attention deficit disorders.
The study, published in the Journal of Neuroscience, used various brain imaging techniques to show exactly how the visual cortex and parietal cortex send direct information to each other through white matter connections in order to specifically pick out the information that you want to see.
"We have demonstrated that attention is a process in which there is one-to-one mapping between the first place visual information comes from the eyes into the brain and beyond to other parts of the brain," said Adam S. Greenberg, postdoctoral fellow in the Dietrich College of Humanities and Social Sciences’ Department of Psychology and lead author of the study.
(Click on the title to read the full article)