Links for Keyword: Movement Disorders
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When a faulty protein wreaks havoc in cells and causes disease, researchers are usually quick to point the finger at a wayward gene. Now scientists are learning that some neurodegenerative diseases can develop even though a gene is perfectly normal. The diseases can be caused when the genetic instructions contained in the gene are not executed properly, leading to a lethal buildup of malformed proteins in brain cells. The new studies by Howard Hughes Medical Institute (HHMI) investigator Susan L. Ackerman and colleagues at The Jackson Laboratory point to a novel mechanism behind the buildup of the toxic sludge that accumulates in neurons. Researchers have long known that neurodegenerative disorders can be caused by the gradual yet persistent accumulation of misfolded proteins in neurons that eventually triggers cell death. But this new mechanism points to errors in executing the genetic instructions, which are distinct from known causes of neurodegenerative diseases, such as Alzheimer's and Huntington's diseases. HHMI investigator Susan L. Ackerman and her colleagues reported their findings in an advance online publication of the journal Nature on August 13, 2006. Ackerman's group collaborated on the studies with co-author Paul Schimmel at The Scripps Research Institute. The researchers made their discovery by studying mice with a mutation called sticky (sti). Although named for the sticky appearance of their fur, the mice harbor much more serious problems beneath their unkempt coats: poor muscle control, or ataxia, due to death of Purkinje cells in a region of the brain called the cerebellum. © 2006 Howard Hughes Medical Institute.
Howard Hughes Medical Institute (HHMI) researchers have discovered a critical function for a protein involved in spinal muscular atrophy (SMA), the number one genetic killer of children under the age of two. The disease is caused when a key protein loses its ability to promote the survival and vigor of motor neurons. According to the Families of Spinal Muscular Atrophy organization, spinal muscular atrophy affects 1 in 6,000 newborns, causing progressive muscle weakness, wasting, or atrophy as motor neurons degenerate. August is National Spinal Muscular Atrophy Awareness Month. In an article published in the July 21, 2006, issue of the journal Molecular Cell, researchers led by Gideon Dreyfuss, a Howard Hughes Medical Institute investigator at the University of Pennsylvania School of Medicine, report that they now know the identity of a protein that is crucial for recognizing specific RNA molecules needed to process genetic information inside the cell. This process breaks down in people who have SMA. In 1994, researchers discovered that the gene, survival of motor neurons (Smn), is deleted or mutated in people with SMA. This observation strongly suggested that reduced levels of or mutations in the SMN protein cause spinal muscle atrophy. Dreyfuss and his colleagues subsequently showed that the SMN protein is needed by all cells to produce messenger RNA (mRNA). Production of mRNA is a critical step in gene expression, and ultimately, in the production of functional proteins. Specifically, the SMN protein plays a crucial role in the genesis of mRNA from a precursor called pre-mRNA. The conversion of pre-mRNA to mRNA takes place in the cell nucleus during a process called splicing. © 2006 Howard Hughes Medical Institute.
By Rossella Lorenzi, Discovery News Abraham Lincoln may have carried a genetic mutation responsible for the neurological disorder ataxia, according to U.S. researchers who screened descendants of the 16th president. Laura Ranum, a genetics professor at the University of Minnesota, and colleagues discovered that a type of ataxia, called Spinocerebellar ataxia type 5 (SCA5), is linked to a mutation in an amino-acid protein which plays an important role in maintaining the health of nerve cells. The gene breakthrough was made thanks to DNA from the Lincoln family: the researchers identified the mutation in an 11-generation family descended from the president's paternal grandparents, Capt. Abraham Lincoln and Bathsheba Herring. Overall, Ranum examined and collected DNA samples from 299 Lincoln family members and found that about a third have ataxia. "We are excited about this discovery because it provides a genetic test that will lead to improved patient diagnoses and gives us new insight into the causes of ataxia and other neurodegenerative diseases, an important step towards developing an effective treatment," Ranum said in a statement. © 2006 Discovery Communications Inc.
By RANDOLPH E. SCHMID WASHINGTON -- A new method of slowing the most common inherited nerve disease may point the way for novel treatments for nerve disorders. Researchers working with rats retarded the progression of CMT, which gradually reduces the ability to use the arms and legs and affects about one in 2,500 Americans. The team found success using a chemical that blocks a protein associated with more than half of all cases of CMT. People with the most common form of CMT have a genetic defect that causes overproduction of that protein. Copyright © 2003, The Associated Press
Possible link between this orphan disease and neurodegenerative disorders considered | By Brendan A. Maher A movement disorder can start as a twinge. A child's leg turns in while walking. Writing becomes difficult, painful. For many, these types of diseases--broadly termed dystonias--progress no further than persistent muscle cramps. Yet in many children affected by rare, heritable, early-onset dystonia, a generalized movement disorder called torsion dystonia develops as well. The disorder can affect the entire body: Opposing muscles work against each other, twisting the posture, causing repetitive movements, or contorting arms and legs into unnatural positions. Oftentimes, the earlier in life symptoms appear, the worse they get. To uncover the roots of this dominant trait, which has only 30% to 40% penetrance, researchers spent more than 15 years studying afflicted, diverse families and a population of Ashkenazi Jews to zero in on a responsible mutation: a three-basepair deletion in DYT1 that appears exactly the same across ethnic groups.1 Recent efforts to elucidate the function for torsinA--the protein this gene encodes--reveal that torsins may act as molecular chaperones, altering protein folding and clearing aggregates from living cells. In worms, torsins alleviate engineered poly-glutamine clumps,2 and in cell culture, torsinA suppresses a-synuclein aggregation.3 These results and others reveal ties to troublesome neurodegenerative disorders such as Parkinson, Huntington, and Alzheimer disease. Protein aggregates are hallmarks of these diseases, but their role remains controversial. Likewise, torsinA's role in clearing the aggregates is murky, and such clumps are not even found in patients with dystonia. Yet, some draw parallels between torsion dystonia and Parkinson disease: Uncontrollable movements are common to both, and some treatments, including deep-brain stimulation, seem to ameliorate symptoms, even though dystonia is not a neurodegenerative disease. ©2003, The Scientist Inc.
With some practice, it's not that hard to balance a baseball bat on the end of your finger. But try to poise a pen or a short stick, and the task becomes rather difficult. That's because a smaller object moves more quickly--at speeds that approach the time required to carry out corrective motions. Now findings published in the October 7 issue of Physical Review Letters suggest that random movements induced by the nervous system can help keep a stick balanced on a fingertip. © 1996-2002 Scientific American, Inc.
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 2707 - Posted: 06.24.2010
Movements faster than your reaction time stop a stick falling off your finger. PHILIP BALL There's more to balancing tricks than quick reactions. Most of the tiny movements we make to balance a stick on a fingertip happen faster than our typical response time, say Juan Cabrera and John Milton of the University of Chicago, thanks to noise in our nervous system.1 Cabrera and Milton think that this mechanism could apply to any problem of balance. Random movements may explain how a tightrope walker stays aloft, for instance. Robotics engineers could make their machines more stable by injecting a little noise into their systems. Using fast cameras that detect infrared light, Cabrera and Milton filmed the motion of a stick with reflective ends, balanced on end on a person's fingertip. Light reflected from the ends enabled them to measure fluctuations in the stick's angle from the vertical. © Nature News Service / Macmillan Magazines Ltd 2002
Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 2693 - Posted: 06.24.2010
A freak accident left Blake Harper paralyzed and bankrupt. But he vows to make a comeback. Mike Roberts The Province A few days after his first birthday in a wheelchair, 29-year-old Blake Harper will crawl into Okanagan Lake and attempt to swim a two-kilometre stretch of the lake's choppy waters. A sadder sight will not be seen on the lake that day -- a young man dragging his useless legs through the water while on the shore his friends cheer and his mom and sister sob for they don't know what: joy that he's so alive; sadness that he's so irreparably damaged. Before he joined the Spinal Cord Injury Club of Canada last spring (36,000 members and growing), Blake Harper was a strapping young carpenter, a natural bodybuilder who loved extreme sports, liked to travel and dreamed of one day opening his own scuba shop. © Copyright 2002 The Province
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 13: Memory, Learning, and Development
Link ID: 2569 - Posted: 06.24.2010
The muscle destruction associated with Duchenne muscular dystrophy (DMD), the most common childhood form of muscular dystrophy, is halted in mice when supplemental amounts of a naturally occurring enzyme are added to the skeletal muscle. These results from researchers at the University of California, San Diego (UCSD) School of Medicine are published in the April 16, 2002 issue of the journal Proceedings of the National Academy of Sciences. Muscle wasting associated with DMD was inhibited after the UCSD team added an enzyme called CT GalNAc transferase to skeletal muscles in mice bred to develop DMD. Normally, CT GalNAc transferase is expressed in another area of the muscle, the neuromuscular junction, where nerves send impulses to muscle fiber. The UCSD team was able to re-position the enzyme so that it was available in the DMD-vulnerable skeletal muscle, which is the structural tissue that supports body movement. Copyright ©2001 Regents of the University of California. All rights reserved.
Myasthenia gravis finding may lead to cure and shine light on other autoimmune diseases such as type 1 diabetes and rheumatoid arthritis GALVESTON, Texas-Researchers here have identified a critical element in the molecular process responsible for the neuromuscular disease myasthenia gravis. The discovery could lead to a possible cure for the muscle-weakening disease and to important insights into other autoimmune disorders such as rheumatoid arthritis, type 1 diabetes, lupus and multiple sclerosis. Myasthenia gravis, which afflicts about 36,000 Americans, causes a loss of muscle strength, which at worst can make even the smallest movements difficult. It occurs when the immune system mistakenly attacks molecules called acetylcholine receptors that muscle cells use to receive chemical signals from nerves. In an article appearing April 15 in The Journal of Clinical Investigation, scientists Premkumar Christadoss, Huan Yang, Elzbieta Goluszko, Teh-Sheng Chan and Mathilde Poussin, all of the University of Texas Medical Branch at Galveston (UTMB), pinpoint the specific part of the human acetylcholine receptor that evokes the strongest response from the human immune cells initiating such "friendly fire" attacks. Copyright © 2001, 2002 The University of Texas Medical Branch.
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 1865 - Posted: 06.24.2010
Paralysis partly overcome by spinal stimulation. HELEN PEARSON A partially paralysed man has walked to the shops with the help of tiny electric shocks to his spine. With training, doctors hope to help other paraplegics walk again. Richard Herman and his colleagues helped a wheelchair-bound quadriplegic follow a walking rhythm by holding him over a moving treadmill. He paced 50 metres slowly - but the effort was exhausting. Zapping his spine while he was walking, slashed his pace time. The team planted pen-width electrodes in his lower back and gave low-level electrical stimulation1. "He began to walk 100, 200 metres," says Herman, of Arizona State University in Tempe. * Herman, R. et al. Spinal cord stimulation facilitates functional walking in a chronic incomplete spinal cord injured. Spinal Cord, 39, (2002). © Nature News Service / Macmillan Magazines Ltd 2002
A gene that causes a fatal childhood brain disorder can also cause adults to develop peripheral neuropathy, a condition resulting in weakness and decreased sensation in the hands and limbs, according to a study by researchers at the National Institutes of Health and other institutions. The study is the first to show that different mutations in the same gene cause the two seemingly unrelated disorders. Inherited peripheral neuropathies are a diverse group of disorders that cause loss of muscle tissue in the hands, feet, and lower legs of affected patients, usually starting in adulthood. Various genetic causes have been identified for Charcot-Marie-Tooth disease (CMT) (http://www.nature.com/ejhg/journal/v17/n6/pdf/ejhg200931a.pdf.), the broad category of inherited peripheral neuropathy that affects approximately 125,000 people in the United States. The peripheral nervous system consists of nerves that reside or extend outside of the brain and spinal cord. In the current study, the researchers determined that persons with a CMT-like neuropathy have a mutation in the same gene that causes Menkes disease, a severe brain disorder that begins in infancy and is fatal if not treated. This gene, called ATP7A, codes for a protein needed to move the trace metal copper between different compartments within the body's cells, or out of cells altogether. "The findings provide insight into how peripheral nerves function and may ultimately lead to new treatments for some peripheral neuropathies," said Alan E. Guttmacher, M.D., acting director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH Institute that collaborated in the study.
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 13: Memory, Learning, and Development
Link ID: 13867 - Posted: 03.15.2010
Scientists believe they have made a breakthrough in the treatment of a severe muscle disease that causes floppy baby syndrome. Most babies born with the rare disorder are severely paralysed and the majority die before the age of one. The Australian team was able to cure affected mice by replacing a missing muscle protein. A UK expert said the findings, in the Journal of Cell Biology, could lead to improved movement for affected babies. The team focussed on proteins called actins. A gene called ACTA1 controls the production of actin in skeletal muscles. It is key to allowing muscles to contract, but children with this disease have flawed versions of the gene and so the protein is not produced. However, the scientists had seen that some children with floppy baby syndrome were not totally paralysed at birth. When these children were studied, it was found that heart actin - another form of the protein - was "switched on" in their skeletal muscles, when that would not normally be the case. Heart actin is found in skeletal muscles while the baby is developing in the womb, but has almost completely disappeared by birth. The researchers found it was possible to cure mice genetically engineered to have the recessive form of the muscle disorder by replacing the missing skeletal muscle actin with heart actin. Dr Kristen Nowak, of the Western Australian Institute for Medical Research, who led the study, said: "The mice with floppy baby syndrome were only expected to live for about nine days, but we managed to cure them so they were born with normal muscle function, allowing them to live naturally and very actively into old age. This is an important step towards one day hopefully being able to better the lives of human patients - mice who were cured of the disease lived more than two years, which is very old age for a mouse." (C)BBC
The race to create more human-like robots stepped up a gear this week as scientists in Spain set about building an artificial cerebellum. The end-game of the two-year project is to implant the man-made cerebellum in a robot to make movements and interaction with humans more natural. The cerebellum is the part of the brain that controls motor functions. Researchers hope that the work might also yield clues to treat cognitive diseases such as Parkinson's. The research, being undertaken at the Department of Architecture and Computing Technology at the University of Granada, is part of a wider European project dubbed Sensopac Sensopac brings together electronic engineers, physicists and neuroscientists from a range of universities including Edinburgh, Israel and Paris with groups such as the German Aerospace Centre. It has 6.5m euros of funding from the European Commission. Its target is to incorporate the cerebellum into a robot designed by the German Aerospace Centre in two year's time. The work at the University of Granada is concentrating on the design of microchips that incorporate a full neuronal system, emulating the way the cerebellum interacts with the human nervous system. Implanting the man-made cerebellum in a robot would allow it to manipulate and interact with other objects with far greater subtlety than industrial robots can currently manage, said researcher Professor Eduardo Ros Vidal, who is co-ordinating work at the University of Granada. (C)BBC
Walking while holding a conversation and writing a letter whilst thinking about its content: we perform many actions without even thinking about them. This is possible due to the cerebellum. It regulates the automation of our movements and as a result the cerebrum can perform other tasks. However, how the cerebellum performs this task is not clear. Dutch researcher Angelique Pijpers reconstructed a part of cerebellar functioning in rats and investigated how it mediates in the control of hind limb muscles. Such research might in future provide a better understanding of how the elderly move. Pijpers and her colleagues investigated which processes took place inside and outside of the cerebellum: how does it channel information and process this into a signal to the muscles? Subsequently they investigated which parts of the cerebellum are involved in regulating the activity of a single muscle. Furthermore, they examined the consequences of inactivation of one or more parts of the cerebellum on the functioning of this muscle. Nerve cells in the cerebellum receive two types of signals. Through the climbing fibres, signals from a specific structure in the brain stem are transmitted to Purkinje cells located in the cerebellar cortex. Mossy fibres transmit signals from various parts of the central nervous system to the granule cells of the cerebellar cortex. Pijpers reconstructed the modular anatomy of the cerebellum by injecting small quantities of traceable substances. This allowed mapping of different 'stations' of the information pathway.
By Michael Purdy -- An epilepsy drug that has been on the market for decades can ease the symptoms of adult sufferers with a genetic disorder that seriously weakens muscles. Scientists at Washington University School of Medicine in St. Louis retrospectively reviewed results from off-label use of the drug valproate to treat seven adult spinal muscular atrophy (SMA) patients. Clinicians offered the drug to patients on the basis of research conducted elsewhere that showed the drug increased levels of a key protein in cell cultures. "The treatment has been fairly successful," says lead author Chris Weihl, M.D., Ph.D., a postdoctoral fellow in neurology. "The drug appeared to be well-tolerated and increased the strength of the patients who took it." The study, now available online, will appear in the August 8 issue of Neurology. Weihl notes that a larger, prospective trial is needed to firmly establish valproate as a treatment of choice for sufferers of this type of SMA. Such trials are already underway elsewhere in pediatric patients who suffer from a different type of SMA that begins earlier in life. Weihl and his colleagues are concerned that valproate may not work as well in those patients. They wanted to make sure that researchers did not discard the possibility that valproate could help older sufferers even if the trials in pediatric patients went poorly.
Researchers at the University of Minnesota Medical School have discovered the gene responsible for a type of ataxia, spinocerebellar ataxia type 5 (SCA5), an incurable degenerative brain disease affecting movement and coordination. This is the first neurodegenerative disease shown to be caused by mutations in the protein â-III spectrin which plays an important role in the maintaining the health of nerve cells. The scientific discovery has historical implications as well--the gene was identified in an 11-generation family descended from the grandparents of President Abraham Lincoln, with the President having a 25 percent risk of inheriting the mutation. "We are excited about this discovery because it provides a genetic test that will lead to improved patient diagnoses and gives us new insight into the causes of ataxia and other neurodegenerative diseases, an important step towards developing an effective treatment," said Laura Ranum, Ph.D., senior investigator of the study and professor of Genetics, Cell Biology and Development at the University of Minnesota. Understanding the effects of this abnormal protein, which provides internal structure to cells, will clarify how nerve cells die and may provide insight into other diseases, including amyotrophic lateral sclerosis (Lou Gehrig's disease) and Duchenne muscular dystrophy. The research will be published in the February print issue of Nature Genetics, and posted online Jan. 22, 2006.
A Devon scientist is developing a test to diagnose and monitor brain disorders in children using eye movements. Professor Chris Harris, from the University of Plymouth, has been seeing youngsters with some of the country's rarest diseases. Damage in various parts of the brain often leads to eye movement disorders. He hopes to develop a standard test so that babies and the most seriously ill children - who are often the most uncooperative - can be diagnosed. The earlier some conditions are treated, especially those with diseases that are only going to get worse, the better the possible outcome for the children involved. A test would also mean new types of medication can be monitored for clinical trials. Prof Harris' research has been funded by a charity called Cerebra, for brain-injured children. He is particularly interested in diagnosing so-called neurometabolic diseases, which are very difficult to diagnose. They are a group of 1,500 often terminal diseases that can be caused by chemical imbalances in the body which ultimately cause brain cells to die. He uses a computer-controlled chair with electrodes attached to the patient's head to see how "flicks" of the eye are affected by various medical conditions. He said: "The way we control our eye movements depends on brain function. Damage in various parts of the brain often leads to eye movement disorders. So by looking at abnormal eye movements we can pick up on problems before they become too severe. (C)BBC
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 8199 - Posted: 11.21.2005
By JANE E. BRODY Paula Schneider was 38 when she developed what doctors first thought was carpal tunnel syndrome. But soon the trouble she had moving her right arm spread to her neck and back and then the whole body. She lost control of her limbs, head and torso, leaving her unable to walk, sit, eat or do much of anything. It was as if her entire body had been inhabited by jitterbugs that determined her every move. More Personal Health Columns "I couldn't eat like a normal person, brush my teeth or drink from a glass because it would break when I tried to put it down," Ms. Schneider recalled recently at a demonstration on movement disorders at Beth Israel Hospital in New York. The cause, she eventually learned, was a severe movement disorder called generalized dystonia. Various medications helped for a while. So did multiple localized injections of Botox to disrupt the flow of nerve impulses to muscles that were spastic or excessively contracted. But the benefits were limited and short-lived. She said she spent 12 years in excruciating pain. Copyright 2005 The New York Times Company
A brain area presumed to be involved only in co-ordinating movement also controls higher functions, such as vision, mounting evidence suggests. Traditionally, higher mental processing has been seen as the cerebrum's job - the evolutionary newest and largest part of the brain. The cerebellum or "little brain", which sits below the cerebrum, was thought to control balance and movement. A study of brain-injured infants shows this view is too simplistic. The research in Pediatrics looked at 74 babies born prematurely who had varying degrees of brain damage. The Harvard team from the Children's Hospital in Boston used magnetic resonance imaging (MRI) brain scans to look at the injuries in detail. When there was injury to the cerebrum, the cerebellum also failed to grow to a normal size. When the cerebral injury was confined to one side, it was the opposite half of the cerebellum that failed to grow normally. Similarly, when injury occurred in one cerebellar hemisphere, the opposite side of the cerebrum was smaller than normal, which the researchers said suggested there was an important developmental link between the two parts of the brain. Other work by Dr Catherine Limperopoulos and her colleagues suggests in addition to motor problems, children born with cerebellar injuries have problems with higher cognitive processes such as communication, social behaviour and visual perception. (C)BBC
Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 5: The Sensorimotor System
Link ID: 8016 - Posted: 10.10.2005