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by Linda Geddes "Moonwalking" mice may provide insights into the genetic causes of a rare debilitating condition called cerebellar ataxia. The illness affects the cerebellum – the part of the brain that controls movement and balance. The mice, which are engineered to express a mutated protein that causes neurons in the cerebellum to die, move backwards when they try to walk forwards on a smooth surface. The same neurons are destroyed in cerebellar ataxia, which causes unsteadiness and loss of co-ordination. Moonwalking – made famous by Michael Jackson – is a dance move where someone appears to walk forwards but actually slides backwards. The mice seem to do it because they place their feet further apart than normal as they walk, in order to maintain their balance. Humans with cerebellar ataxia have trouble coordinating their movements, although "I don't think there are any human patients out there who walk backwards," says Esther Becker of the University of Oxford, who led the study. "The million dollar question is whether mutations of this gene also occur in humans with cerebellar ataxia," says Becker, who is currently screening patients with genetic forms of the condition to find out. If they do, it could pave the way towards new treatments. © Copyright Reed Business Information Ltd.
EAST LANSING, Mich. — A mouse created by Michigan State University scientists studying a disease thought to be a neurological disorder that weakens men has exposed two surprises: Testosterone appears to be the culprit and it’s attacking muscles, not nerves. The muscles of male mice genetically engineered in the laboratory of Cynthia Jordan, professor of neuroscience and psychology, have extra receptors that latch onto testosterone – a trick that left researchers anticipating mouse versions of bulked up body builders. Instead, these mice developed into shrunken weaklings. More significantly, their condition precisely imitated a rare human condition called Kennedy’s Disease. The results, reported in the Oct. 29 online issue of the Proceedings of the National Academy of Sciences, not only directly contradict conventional wisdom about the root of Kennedy’s Disease, but also offer significant hope. Researchers say these new results make a strong case that Kennedy’s Disease is a muscular disease rather than a neurological disease, and put testosterone in the category of cause, not cure. “When we started studying this little wimp mouse, we were surprised to find that we inadvertently created a model for Kennedy’s Disease,” Jordan said. “Our story provides some hope, because it’s an easier problem to target muscles therapeutically than the motor neurons in the spinal cord. Our sick mice get well when we take testosterone away from them.”
Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 8: Hormones and Sex
Link ID: 10924 - Posted: 06.24.2010
ST. PAUL, MN – Treating Guillain-Barré syndrome early may speed up the recovery time, according to a guideline developed by the American Academy of Neurology. The guideline is published in the September 23 issue of Neurology, the scientific journal of the American Academy of Neurology. Treatment should begin within two to four weeks after the first symptoms appear. Guillain-Barré syndrome (GBS) causes rapid onset of weakness and often paralysis of the legs, arms, face and breathing muscles. It is the most common cause of rapidly acquired paralysis in the United States, affecting between one and four people in every 100,000 each year. Guillain-Barré is an autoimmune disease in which the body’s immune system attacks the nervous system. The human body produces proteins called antibodies to fight off infections. In GBS, the body produces extra antibodies that become misdirected and attack and damage the nerves.
St. Paul, MN – As the nation gears up for another season of West Nile virus, a new study extends the understanding of the clinical spectrum of West Nile symptoms, and points to extreme muscle weakness or paralysis as a significant cause of complications in affected patients. The study appears in the July 8 issue of Neurology, the scientific journal of the American Academy of Neurology. Detailed examination of 23 patients at the Cleveland Clinic revealed that among the earliest symptoms in 26 percent was a rash, which helped distinguish the disease from another rapid-onset paralytic disorder, Guillain-Barre syndrome. Misdiagnosis is still very common for West Nile virus, according to lead study author Lara Jeha, MD. Other early symptoms include low back pain, limb pain, and gastrointestinal complaints, typical of many viral illnesses. All patients developed fever at some point in their illness. Half the patients developed muscle weakness, which developed rapidly, over the course of three to eight days. For many patients, this progressed to involve all four limbs. In one patient, weakness remained the primary symptom even in advanced disease. Nine patients required mechanical ventilation due to weakness of the breathing muscles. Previous studies had described flaccid paralysis with West Nile virus infection, but details about the various aspects of this weakness were very limited.
DALLAS – – Researchers from UT Southwestern Medical Center at Dallas and the Mayo Clinic have discovered a novel genetic mutation that leads to a debilitating muscle condition known as myasthenia. Myasthenia, a severe form of muscle weakness, usually results from an autoimmune attack against the nerve-muscle junction in which the nerve's communication to the muscle is broken down. In a study appearing this week in the online early edition of Proceedings of the National Academy of Sciences, researchers unveil a new cause discovered in a single patient: a genetic mutation leading to a shutdown in muscle responsiveness to the nerve's electrical impulses. "This was a surprise in that it's a totally different mechanism for a well-researched disease," said Dr. Stephen Cannon, chairman of neurology at UT Southwestern, who studied the consequences of the genetic mutation. "Until this study, every single case of myasthenia ever examined had been attributed to a reduction in what's called the safety factor of neurotransmission – or how reliably the nerve talks to the muscle."
An altered mouse model of Duchenne muscular dystrophy, developed to have high levels of insulin-like growth factor I (IGF-I), has shown increases in muscle mass of at least 40 percent and other changes that could herald a possible treatment for secondary symptoms of the disease in humans. The new mouse, developed with support from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the Muscular Dystrophy Association, has also resulted in reduced amounts of muscle-replacing fibrous tissue and enhanced biological pathways associated with muscle regeneration. Duchenne muscular dystrophy, a genetic muscle-wasting disease caused by mutations in the gene for the protein dystrophin, results in repeated cycles of muscle damage and insufficient muscle regeneration, leading to gradual replacement of muscle by fibrous tissue. Since IGF-I is known to help regenerate muscle and enhance biological pathways for making proteins, the University of Pennsylvania's H. Lee Sweeney, M.D., and his colleagues tested its effects by creating a new mouse model – a cross between a strain with muscular dystrophy symptoms and another with high levels of IGF-I. The hybrid mouse showed not only increases in muscle mass and muscle force generation, but also reduced muscle cell death, a combination that could have significant treatment implications.
By JANE E. BRODY “Essential” usually means vital, necessary, indispensable. But in medicine, the word can assume a different cast, meaning inherent or intrinsic, not symptomatic of anything else, lacking a known cause. Since the mid-19th century, “essential tremor” has been the diagnosis for a disorder of uncontrollable shaking — usually of the hands but sometimes of the head and other body parts, or the voice — that is not due to some other condition. And without knowing what causes it, doctors have been slow to come up with treatments to subdue it. As a result, millions of individuals suffer to varying degrees with embarrassment and humiliation, social isolation and difficulties holding down a job or performing the tasks of daily life. When you cannot drink a glass of water or eat soup without spilling it because your hand shakes violently, you are unlikely to join others for a dinner out. When you have to depend on someone else to button your shirt or zip your jacket, you may not go out at all. Wherever those with essential tremor go, people are likely to stare at them and assume they have a drug or alcohol problem, said Catherine Rice, executive director of the International Essential Tremor Foundation in Lenexa, Kan. (Call it at 888-387-3667 or visit its Web site: www.essentialtremor.org.) Now, thanks to the devoted efforts of a few researchers here and abroad, all this may change. Recent studies have begun to unravel the mysteries of essential tremor, and “essential” may someday be dropped from its name. Copyright 2009 The New York Times Company
By RONI CARYN RABIN It may be hard to fathom, but in the haystack of government health statistics that track cancer, car accidents, twin births to women over 40, fat teenagers and people who quit smoking, there has been no reliable estimate of the number of Americans affected by paralysis. Until now. A study to be released on Tuesday by the Christopher and Dana Reeve Foundation reports that far more Americans than previously estimated are paralyzed to some degree: 5.6 million people, representing 1.9 percent of the population, or roughly 1 in 50 Americans. Previous estimates — or “guesstimates,” as some have called them — hovered around 4 million at most, and some were as low as 1.4 million. “Nobody had any idea what the numbers were, because no one ever tried to find out,” said Joseph Canose, vice president for quality of life at the Reeve Foundation’s Paralysis Resource Center, who led the study. “There were many different ways of counting it, and there was no common definition, and the numbers were all over the place.” But the figures, which could have enormous implications for public policy, research financing and health care, are already causing controversy, because the estimates for paralysis caused by certain diseases and conditions differ drastically from long-accepted numbers. Copyright 2009 The New York Times Company
by Joyce Gramza It’s been 20 years since the discovery of the gene that causes the most common type of Muscular Dystrophy — Duchenne MD — and patients are still waiting for a cure. "The mutation causes muscle fibers to pull away from each other and with progressive use of your muscles in these patients it eventually leads to muscle damage, severe muscle damage," explains Dean Burkin, assistant professor of pharmacology at the University of Nevada, Reno School of Medicine. Gene therapy to replace the faulty dystrophin gene might be a solution, but Burkin and his colleagues are excited about a simpler and potentially safer approach based on work they are publishing in this week’s Proceedings of the National Academy of Sciences. "This could be an IV drug for the patients if the work in the mouse models that we’ve been using translates to human studies," Burkin says. "That would allow a fair ease of treatment for the patients…. We’ve obviously got to do some safety tests and there’s still a few studies that we need to do. But in the field there are a number of drugs including ours that are being developed. "These patients, especially, have been waiting a long time for new therapies to come about and I think we’re at the cusp now." ©2009 ScienCentral
By DIANA MICHÈLE YAP In my dreams, I can walk. Awake, I lie in bed because I have to — on my back, or on my side. I shift positions. I’ve learned I’m lucky I can do that. Sometimes I’m so tired that simply lying in bed is not restful enough. Can I be any more horizontal? Can my atrophied limbs sink any lower into the sheets, the mattress that molds to my form? I imagine falling through the mattress, but realize it would probably hurt when I hit the floor. I never get bored, lying there. Just sad. Last year I lost my ability to walk. By the time I finally learned I had osteosclerotic myeloma, part of POEMS syndrome (a rare blood disorder whose initials stand for five of its features, including polyneuropathy, or nerve damage), I was weaker than I’d ever been. I was nearly unable even to use my hands. None of it registered as suffering, until this past spring, as I began to write these words. Perhaps I’ve been in shock. I recognize that I don’t live in a war zone, that there are more aggressive cancers. I’m told about others locked in their disabled bodies who produce great work, and even play sports. But I am not extraordinary; I’m no hero. The horror of my situation is the opposite of the happy ending I wished for in high school, half a lifetime ago. At 35, I’m mostly confined to the bed and the wheelchair. Twice a week I go to physical therapy. Copyright 2008 The New York Times Company
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: 12394 - Posted: 06.24.2010
CHICAGO - U.S. scientists have created the first human model for studying a devastating nerve disease, which allows them to watch how the disease develops and could help researchers find a way to treat it. Using skin cells from a child with spinal muscular atrophy, a genetic disease that attacks motor neurons in the spinal cord, researchers grew batches of nerve cells with the same genetic defects. The finding allowed scientists to watch the nerve cells die off. "Now we can start from the beginning of development and replay the disease process in the lab dish," Clive Svendsen of the University of Wisconsin-Madison said in a telephone interview. The finding, reported on Sunday in the journal Nature, marks the latest advance in research that reprograms ordinary cells to look and act like embryonic stem cells — the master cells of the body that can produce any type of tissue or blood cell. Spinal muscular atrophy is the most common cause of childhood death caused by a genetic mutation, Svendsen said. It is caused by a deficiency of a protein called SMN, for survival of motor neurons. "That SMN protein is important for motor neuron survival. They are the cells that make muscles move," Svendsen said. Copyright 2008 Reuters.
Researchers at the Howard Hughes Medical Institute are unveiling a new resource that they say will speed scientists' understanding and treatment of a group of inherited disorders called ataxias that kill cells in the brain, causing loss of balance, coordination and often death. The scientists are making new data available on hundreds of interacting proteins that are involved in dozens of inherited forms of ataxia. The approach to mapping the global set of interacting proteins—called an “interactome”—could also be applied to disorders as diverse as Parkinson's disease, diabetes, and hypertension. Howard Hughes Medical Institute investigator Huda Y. Zoghbi and her colleagues reported on their studies in an article published in the May 18, 2006, issue of the journal Cell. Zoghbi and her colleagues at the Baylor College of Medicine collaborated on the studies with researchers from Harvard Medical School and the University of Notre Dame. Since proteins are the major machines that work inside cells, understanding how they interact may give researchers an opportunity to learn how they can go awry and cause disease. Furthermore, understanding these interactions offers scientists targets for drugs that can help restore normal function to such malfunctioning machinery. © 2006 Howard Hughes Medical Institute.
We all teeter and tip while first learning to walk but, for adults like retired electrical engineer Fred Kawabata — whose sense of balance was damaged when a childhood disease flared up as an adult — a simple stroll becomes something to learn all over again. "When it first struck me I was flat on my back," explains 65-year-old Kawabata from Beaverton, Oregon. "I had vertigo, I was dizzy, I could hardly get out of bed." Almost ten years ago the chicken pox he had suffered as a kid came back in the form of shingles. The virus that lay dormant for all those years in his nerves attacked the vestibular nerves of Kawabata's the inner ear, leaving him rather unsteady on his feet because of a balance disorder. "In about a month, I could get up and walk around although it was still very uncomfortable. It took a couple months before I could be reasonably comfortable walking around," he recalls. "[Now], when I'm walking on a flat surface, I generally don't have to think about it very much. But if I'm on an uneven surface like when I'm hiking and the trail is rough, then I really have to think about it. © ScienCentral, 2000-2006.
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: 8729 - Posted: 06.24.2010
By Aaron J. Sender John Donoghue is building a brain decoder that could transform the lives of people paralyzed by injury or disease. Those who have lost the ability to move their limbs often have perfectly intact brains, so Donoghue hopes to implant a chip that can monitor their brain activity and convert their intentions into computer commands. In its current version, the chip’s 100 hair-thin electrodes listen to neurons firing in an area that controls arm movement and translate the activity into electronic signals. A program then decodes the brain signals into commands that direct a cursor on a computer screen. Donoghue hopes the chip can eventually control appliances or even robotic limbs. “We’re effectively rewiring the nervous system—not biologically but with real wires,” says Donoghue. So far, more than 20 monkeys have been equipped with the implanted chip, and four of them have successfully willed a cursor to follow a moving target. Now Cyberkinetics, the company Donoghue cofounded to develop the device they call BrainGate, is preparing to test it in five paralyzed humans. “People with these kinds of injuries are perfectly capable of leading full and productive lives,” says Donoghue. “They just can’t get their signals out.” Give me the big picture first. How did the idea originate and what problem were you looking to solve? D: I’ve had a long-standing basic science research program that has really been directed at how the brain computes information. In a simpler sense, how do you turn thoughts into action? The way you get at the fundamental activity is by recording with electrodes in the brain. And since it’s a procedure that requires you to introduce that electrode, you have to use a monkey or an experimental animal. A monkey has a motor cortex like ours, and its behaviors are a lot like ours, so we use it as a model. © 2004 The Walt Disney Company.
by Paul Austin The patient was lying placidly on the stretcher with her eyes closed when I introduced myself. “I’m Paul Austin, one of the ER doctors. Can you open your eyes and talk with me?” She raised her eyebrows a few millimeters, not even enough to wrinkle her forehead. Her right eye remained shut, and her left eye opened just enough to expose a narrow sliver of white. She turned her face toward me, her eyes still closed. I looked at her paperwork. She was a 63-year-old woman who said she couldn’t keep her eyes open, had difficulty swallowing, and had fallen four times the day before. She also had complaints of general weakness for about two years. That bothered me. The possible causes of overall weakness could fill a textbook. Yet in cases that have gone on for two years without a diagnosis, doctors often find no physical cause. Her chart noted that she had recently been hospitalized for schizo-affective disorder, which causes symptoms of both schizophrenia and a mood disorder, and had recently been discharged. That concerned me as well. When a psychiatric diagnosis is present, it can distract doctors from looking for an organic cause of symptoms. “Can you open your eyes for me?” I asked again. Her eyebrows moved a millimeter up. “Open them all the way.” Using her index fingers she raised both her upper eyelids. She stared at me, holding her eyelids up with her fingers, her elbows sticking out at her sides.
By BEN DAITZ, M.D. ALBUQUERQUE, In 1598, Joyce Gonzalez’s great- great- great- great -great -great -great -great -great -great -grandfather followed the famous conquistador Juan de Oñate from Spain to Mexico, then north on the Camino Real, the Royal Road to Santa Fe. In the 1800s, one of Mary Ann Chavez’s distant relatives, possibly a French fur trapper and trader from Quebec, also made his way into northern New Mexico. Mrs. Chavez and Mrs. Gonzalez, though not related, share a Hispanic heritage and a fascination with genealogy. They also share the burden of having forebears with genetic diseases that, like the remote mountain villages in this region, have remained largely hidden from medical diagnosis and treatment. Now, thanks to the efforts of patient advocates and the work of a clinic here at the University of New Mexico Medical School, these illnesses are finally being confronted and studied. “We call it the family curse,” said Mrs. Chavez, 73, “and you don’t know you’ve got it until you’re 40 or 50 when your eyelids start to droop, and you begin to have trouble swallowing and get muscle weakness.” The illness is called oculopharyngeal muscular dystrophy, or OPMD, and the largest group of Americans affected are Hispanics living in northern New Mexico. They are descendants of the wandering French-Canadian or, perhaps, early Spanish colonists. Mrs. Chavez’s son, her brother and innumerable aunts, uncles and cousins have all inherited the disease. Copyright 2007 The New York Times Company
ITHACA, N.Y. -- Using a state-of-the-art technique to map neurons in the spinal cord of a larval zebrafish, Cornell University scientists have found a surprising pattern of activity that regulates the speed of the fish’s movement. The research may have long-term implications for treating injured human spinal cords and Parkinson’s disease, where movements slow down and become erratic. The study, "A Topographic Map of Recruitment in Spinal Cord," published in the March 1 issue of the journal Nature, maps how neurons in the bottom of the fish’s spinal cord become active during slow movements, while cells further up the spinal cord activate as movements speed up. By removing specific neurons in the lower spinal cord with laser beams, the researchers rendered the fish incapable of slow movements. By removing nerves further up the backbone, the fish had difficulty moving fast. "No one had any idea that organization like this existed in a spinal cord," said Joseph Fetcho, a Cornell professor of neurobiology and behavior and an author of the study. "Now that we know the pattern, we can begin to ask how that changes in disease states." David McLean, Cornell postdoctoral researcher in Fetcho’s laboratory, was the first person to discover the pattern of neural activation and how it was associated with speed of movement. He is the lead author on the study.
Drug therapy can extend survival and improve movement in a mouse model of spinal muscular atrophy (SMA), new research shows. The study, carried out at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), suggests that similar drugs might one day be useful for treating human SMA. "This study shows that treatment can be effective when started after the disease appears," says Kenneth H. Fischbeck, M.D., of the NINDS, who helped lead the new study. The finding is important because most children with SMA are diagnosed after symptoms of the disease become obvious, he adds. The report appears in the February 22, 2007, advance online publication of The Journal of Clinical Investigation. SMA is the most common severe hereditary neurological disease of childhood, affecting one in every 8,000-10,000 children. Babies with the most common form of the disease, called SMA type I, develop symptoms before birth or in the first few months of life and have severe muscle weakness that makes it difficult for them to breathe, eat, and move. They usually die by age two. Other forms of SMA are not as severe, but still cause significant disability. While some symptoms of SMA can be alleviated, there is currently no treatment that can change the course of the disease. SMA is caused by mutations in a gene called SMN1. Investigators studying the genetics of SMA have found that there is another gene, called SMN2, on the same chromosome. While the normal form of SMN1 produces a full-length functional protein, most of the protein produced by SMN2 is truncated and unable to function. The relatively small amount of normal SMN protein produced by the SMN2 gene can reduce the severity of the disease. Therefore, investigators are searching for drugs that can increase the amount of normal protein produced by this gene.
ST. PAUL, MN -- An anticonvulsant drug typically used to control seizures and neuropathic pain may reduce symptoms among those who suffer from restless legs syndrome (RLS), a movement disorder that affects up to 10 percent of the population. A study published in the November 26 issue of Neurology, journal of the American Academy of Neurology, concludes, “Gabapentin may be a potent agent for treatment of even severe RLS, without the disadvantages of long-term complications of previously favored treatments,” according to study author Diego Garcia-Borreguero, MD, of the Fundacion Jimenez Díaz in Madrid, Spain. RLS is characterized by: an urge to move the legs, generally accompanied by unpleasant sensations; an increase of symptoms during rest and a partial, temporary relief of symptoms through activity; and worsening of symptoms in the evening or at night. Symptoms tend to progress with age. RLS is usually treated with dopaminergic drugs, such as those used with Parkinson’s disease patients. However, the side effects and likelihood of long-term complications have driven the search for RLS treatment options.
Researchers have discovered how the abnormal repetition of a genetic sequence can have disastrous consequences that lead to the death of neurons that govern balance and motor coordination. The studies bolster the emerging theory that neurodegenerative disorders can be caused by having extra copies of a normal protein, not just a mutated one. People who are afflicted with the rare neurodegenerative disorder spinocerebellar ataxia type 1 (SCA1) suffer damage to cerebellar Purkinje cells caused by a toxic buildup of the protein Ataxin-1. Researchers knew that SCA1, Huntington's disease and other related disorders arise because of a “genetic stutter,” in which a mutation causes a particular gene sequence to repeat itself. These abnormal genetic repeats cause the resulting proteins to contain unusually long repetitive stretches of the amino acid glutamine. The new findings, which are published in the August 26, 2005, issue of the journal Cell, provide a molecular explanation for Ataxin-1's assault on cerebellar Purkinje cells. The findings should help to understand a range of diseases, including Huntington's disease, which are caused by an abnormal number of repetitive gene sequences. The discovery may also offer a new conceptual approach to understanding the pathology of Parkinson's disease and Alzheimer's disease, according to Huda Y. Zoghbi, a Howard Hughes Medical Institute investigator at the Baylor College of Medicine. © 2005 Howard Hughes Medical Institute.