Links for Keyword: Movement Disorders
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By Michael Price People with muscular dystrophy tire after even light exercise. Now a study suggests that the exhaustion is caused by an enzyme that is missing from the muscle cell membrane, and the results point to a possible treatment for the condition: Viagra. Every year, about 500 boys in the United States are born with Duchenne muscular dystrophy, the disease's most common form. All forms of muscular dystrophy, which cause skeletal muscles to gradually weaken, result from mutations that overload the body with the enzyme creatine kinase, which breaks down muscle tissue. Researchers have long known that even in milder types of the disease, such as Becker's muscular dystrophy, and in the early stages of Duchenne muscular dystrophy, patients tend to fatigue after relatively minor activities. The briefest walk can leave them far more worn out than would be expected from just having weak muscles. These effects show up in mouse models of the disease, too. About 3 years ago, Kevin Campbell, a biophysicist at the University of Iowa in Iowa City, showed a video of the tired muscular dystrophy mice in his lab at a conference. A chance comment inspired a possible solution. "One of the physicians in the audience said, 'That looks just like my Becker's [muscular dystrophy] patients,' " Campbell recalls. One of the hallmarks of Becker's muscular dystrophy is the loss of an enzyme, neuronal nitric oxide synthase (nNOS), from muscle cell membranes. Campbell wondered whether the deficiency of nNOS might be the source of fatigue. © 2008 American Association for the Advancement of Science.
Kerri Smith A monkey's paralysed wrist can be moved and controlled by electrical signals artificially routed from its brain, according to scientists who say that their experiment is a step towards helping paralysed people to regain the use of their limbs. Previously, scientists have been able to train monkeys to move robotic arms using signals routed from electrodes in their brains1. This involved decoding the activity of tens of neurons at a time to replicate actions such as grasping, and required considerable computing power. Now, Chet Moritz and his colleagues at the University of Washington in Seattle have used similar signals to deliver direct electrical stimulation from just one neuron to a paralysed muscle. They first implanted a number of electrodes in the motor cortex of two macaque monkeys. Each electrode picked up signals from a single neuron, and those signals routed through an external circuit to a computer. The neuronal signals controlled a cursor on a screen, and the monkeys were trained to move the cursor using only their brain activity. The scientists then temporarily paralysed the monkeys' wrist muscles using a local anaesthetic. They re-routed the signals from the electrodes to deliver electrical stimulation to the wrist muscles, and found that the monkeys could control their previously paralysed limbs using the same brain activity. The monkeys learnt to do this in less than an hour, the team report in Nature2. © 2008 Nature Publishing Group
By Sandra G. Boodman Bruce Munro wonders how things might have turned out if he hadn't lost it and dialed 911. The retired obstetrician had watched with mounting alarm as his wife, Bettie, seemed to get sicker by the day. For decades her health had been stable, regulated by medicines she took to control her cholesterol, blood pressure, Type 2 diabetes, a thyroid condition and a mood disorder. But in March 2006, Bettie Munro had developed a tremor that became very bad very fast. Doctors assumed she was suffering from a rapidly progressive case of Parkinson's disease, but the neurologist treating her was baffled about why the increasingly potent drugs he prescribed didn't seem to help. On Dec. 22, 2006, while Munro was getting his wife dressed for the day, he snapped. She had fallen three times and could no longer feed herself. "I thought, 'This is it, I can't handle this at home,' " Munro recalled. He picked up the phone and called for help. An ambulance whisked Bettie Munro from their house in a Loudoun County retirement community to Inova Loudoun Hospital. © 2008 The Washington Post Company
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 11596 - Posted: 06.24.2010
By David Brown Fittingly, the first person to detect a faint signal in all the noise was the interpreter. The 33-year-old woman who worked for eight years working with Spanish-speaking patients at a medical clinic in southern Minnesota noticed something familiar as she translated the story of a young meatpacker last September. Earlier last summer, she had heard a version of it from two other workers at the same slaughterhouse, and had told it to their doctors, who were different from her current patient's. When the consultation was over, she pointed this out. The interpreter's insight set in motion a story, still unfolding, that may be making envious the ghost of Berton Roueche, the legendary chronicler of medical mysteries at the New Yorker magazine. A new disease has surfaced in 12 people among the 1,300 employees at the factory run by Quality Pork Processors about 100 miles south of Minneapolis. The ailment is characterized by sensations of burning, numbness and weakness in the arms and legs. For most, this is unpleasant but not disabling. For a few, however, the ailment has made walking difficult and work impossible. The symptoms have slowly lessened in severity, but in none of the sufferers has it disappeared completely. © 2008 The Washington Post Company
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 5: The Sensorimotor System
Link ID: 11273 - Posted: 06.24.2010
Studies in mice have shown that lithium, a drug widely used to treat mood disorders in humans, can provide relief from the crushing symptoms of a fatal brain disease, according to researchers at the Howard Hughes Medical Institute (HHMI) at the Baylor College of Medicine. A team led by HHMI investigator Huda Y. Zoghbi did a series of experiments in mice that showed lithium, a psychiatric drug used to stabilize mood shifts, can ease the symptoms of spinocerebellar ataxia type 1, an inherited neurodegenerative disorder. Their research article was published on May 28, 2007, in the journal Public Library of Science (PLoS) Medicine. "The results are very exciting," said Zoghbi. "It's really hard to improve multiple symptoms (in a condition). Lithium seems to improve several in this case, not just one." The new findings are important because they suggest it may be possible to use the drug to alleviate deteriorations in motor coordination, learning and memory manifested by the spinocerebellar ataxia. At present, treatments for the condition are limited and patients, who are usually diagnosed in their thirties or forties, experience a gradual decline in motor and memory function and die within a few years of onset of the disease. © 2007 Howard Hughes Medical Institute.
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.