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By Emily Underwood The early signs of Creutzfeldt-Jakob disease (CJD)—a rare, incurable brain disorder caused by infectious, misshapen proteins called prions—are difficult to interpret. At first, people may simply feel depressed and can undergo personality changes or bouts of psychosis. By the time memory failure, blindness, and coma set in, typically within a year of infection, death is usually imminent. Now, researchers report that a simple nasal swab may help physicians detect the disease far more accurately and earlier than current methods. Finding simple, noninvasive diagnostic tests is “one of the holy grails” for CJD and other prion diseases, says biochemist Byron Caughey of the National Institute of Allergy and Infectious Diseases’ Rocky Mountain Laboratories in Hamilton, Montana, who helped lead the new work. Although there’s no cure for CJD, early diagnosis is important because it can help rule out other, treatable disorders, and it allows medical personnel to take precautions that prevent the disease from spreading to others through exposure to brain tissue or spinal fluid, he says. Researchers made a major stride toward better diagnostic methods in 2010, when Caughey and other researchers first described a new technique called the RT-QuIC test. The test requires removing cerebrospinal fluid (CSF) from patients by means of a spinal tap, putting samples into a bath of normally shaped prion proteins, and agitating the solution to encourage any abnormal prion “seeds” in the tissue to latch onto the regular proteins. If even trace amounts of pathogenic protein are present, they rapidly use the normal proteins to create millions of insoluble, fibrous amyloid strands. Researchers believe that these amyloid aggregates, also seen in other neurodegenerative diseases such as Alzheimer’s disease, ultimately cause CJD by interfering with or killing off neurons en masse. After death, the brains of people affected by CJD are so badly damaged that they often resemble Swiss cheese or sponges. © 2014 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 19926 - Posted: 08.07.2014

By ANEMONA HARTOCOLLIS Dozens of Whole Foods stores in the Northeast and a restaurant in New York received beef over an eight-month period that may not have been properly slaughtered to reduce the threat of mad cow disease, federal officials said on Thursday. The producer of the beef, Fruitland American Meat, in Jackson, Mo., recalled thousands of pounds of bone-in grass-fed rib eyes, and two quartered beef carcasses, after federal officials reviewing slaughtering logs found that certain precautions had not been followed. The beef in question was processed between Sept. 5 and April 25, and the meat has the number 2316 inside the Agriculture Department inspection mark. The federal government said the beef posed only a “remote” health hazard, and the cows themselves had shown no evidence of the disease. Fruitland American denied on Thursday that the meat had been improperly handled. The company said the government’s finding was based on a clerical error, in which the age of the cattle had been documented as 30 months or more, when rules on mad cow must be followed, because older cows are believed to be at greater risk. But birth records showed that the cows were in fact no more than 28 months old, a spokesman said. A spokeswoman for the Agriculture Department, Alexandra Tarrant, said the agency was looking into the chance that a clerical error had occurred. The meat was shipped to 34 Whole Foods stores in northern Connecticut, Maine, Massachusetts and Rhode Island. Michael Sinatra, a spokesman for the company, said none of the meat was currently in the stores. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 19726 - Posted: 06.14.2014

By ABIGAIL ZUGER, M.D. Sweet revenge comes in many delectable forms, among them the receipt of accolades for work long scorned. And then to get to tell the whole story at length and without a single interruption — small wonder that the Nobel laureate Dr. Stanley B. Prusiner, a renowned neurologist at the University of California, San Francisco, writes with a cheerful bounce. Once disparaged, his scientific work is now hailed as visionary, and his memoir takes the reader on a leisurely and immensely readable victory lap from then to now. In the process, two stories unfold. The first is the progress of Dr. Prusiner’s thinking on the transmissible proteins he named prions (PREE-ons) in 1982, starting with his first experiments on an obscure disease of sheep and ending with the most recent work linking prions to an array of human neurological catastrophes, including Alzheimer’s disease. The science is convoluted, like the proteins, and for the uninitiated the best way to achieve a rudimentary grasp of the subject is to hear it the way Dr. Prusiner tells it, from the very beginning. But a parallel narrative turns out to be equally fascinating: perhaps not since James D. Watson’s 1968 memoir “The Double Helix“ has the down and dirty business of world-class science been given such an airing. Dr. Watson raised eyebrows with his gossipy account of the serious task of unraveling the genetic code — and he was working in genteel postwar Britain at the time, with experimental science still at least in theory a gentleman’s game. That illusion is long gone: The stakes are considerably higher now, the competition fierce, the pace frantic, and Dr. Prusiner, 71, revisits quite a few of the battles that punctuated his long research career. He was an underachiever in high school and then an achiever in college and medical school, captivated by the laboratory early on. He finished his medical training on the neurology wards in San Francisco, where he met the patient who would set the course of his career: a slim, tanned 60-year-old woman from Marin County who was having trouble unzipping her golf bag. Months later she was dead of Creutzfeldt-Jakob disease, one of several related and invariably fatal neurological diseases (mad cow among them) that leave the brain of the affected human or animal riddled with holes, a useless sponge. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 19632 - Posted: 05.19.2014

|By Beth Skwarecki The protein family notorious for causing neurogenerative diseases such as Parkinson's—not to mention mad cow—appears to play an important role in healthy cells. “Do you think God created prions just to kill?” muses Eric R. Kandel of Columbia University. “These things have evolved initially to have a physiological function.” Kandel's work on memory helped to reveal that animals make and use prions in their nervous systems as part of an essential function: stabilizing the synapses involved with forming long-term memories. These natural prions are not infectious, but on a molecular level they chain up exactly the same way as their disease-causing brethren. (Some researchers call them “prionlike” to avoid confusion.) Now neuroscientist Kausik Si of the Stowers Institute for Medical Research in Kansas City, Mo., one of Kandel's former students, has shown that the prion's action is tightly controlled by the cell and can be turned on when a new long-term memory needs to be formed. Once the prion's chain reaction gets started, it is self-perpetuating, and thus the synapse—where neurons connect—can be maintained after the initial trigger is gone, perhaps for a lifetime. But that still does not explain how the first prion is triggered or why it happens at only certain of the synapses, which play a crucial role in forming memories. Si's work, published February 11 in PLOS Biology, traces the biochemistry of this protein-preservation process in fruit flies, showing how the cell turns on the machinery responsible for the persistence of memory—and how the memory can be stabilized at just the right time and in the right place. © 2014 Scientific American

Related chapters from BP7e: Chapter 17: Learning and Memory; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 19629 - Posted: 05.18.2014

Eighteen neurological patients in North Carolina may have been exposed to an incurable and fatal disorder similar to "mad cow" disease while undergoing surgery at the Novant Health Forsyth Medical Center because surgical instruments were insufficiently sterilized, the hospital said on Monday. Surgeons operated on the 18 patients on January 18 using tools that had not been sufficiently sanitized after they were used on a man suspected of having Creutzfeldt-Jakob Disease (CJD), the hospital in Winston-Salem said in a press statement. "On behalf of the entire team at Novant Health, I apologize to the patients and their families for having caused this anxiety," Jeff Lindsay, president of the medical center, said at a news conference. CJD causes failing memory, blindness, involuntary movement and coma, and kills 90 percent of patients within one year, according to the National Institute of Neurological Disorders and Stroke. The condition is similar to mad cow disease, but is not linked to beef consumption. The incubation period — before initial symptoms surface — can last years, the statement said. After the first sign of symptoms, most patients die within four months, it said The possibility of contracting the disease through surgical exposure is very remote, the hospital said.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 19234 - Posted: 02.11.2014

By Lary C. Walker Clumps of proteins twisted into aberrant shapes cause the prion diseases that have perplexed biologists for decades. The surprises just keep coming with a new report that the simple clusters of proteins responsible for Mad Cow and other prions diseases may, without help from DNA or RNA, be capable of changing form to escape the predations of drugs that target their eradication. Prion drug resistance could be eerily similar to that found in cancer and HIV—and may have implications for drug development for Alzheimer’s and Parkinson’s, neurodegenerative diseases also characterized by misfolded proteins. Prion diseases include scrapie, chronic wasting disease and bovine spongiform encephalopathy (mad cow disease) in nonhuman species, and Creutzfeldt-Jakob disease and fatal insomnia in humans. They are unusual in that they can arise spontaneously, as a result of genetic mutations, or, in some instances, through infection. Remarkably, the infectious agent is not a microbe or virus, but rather the prion itself, a clump of proteins without genetic material. The noxious agents originate when a normally generated protein – called the prion protein – mistakenly folds into a stable, sticky, and potentially toxic shape. When the misfolded protein contacts other prion protein molecules, they too are corrupted and begin to bind to one another. In the ensuing chain reaction, the prions grow, break apart, and spread; within the nervous system, they relentlessly destroy neurons, ultimately, and invariably, leading to death. © 2013 Scientific American

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 5: The Sensorimotor System
Link ID: 18799 - Posted: 10.17.2013

Ewen Callaway As a new study in the British Medical Journal reveals that 1 in 2000 people in the UK may harbour the infectious prion protein which causes variant Creutzfeldt–Jakob disease (vCJD), Nature explains what this means. The usually fatal condition is the human form of bovine spongiform encepalpoathy — dubbed 'mad cow disease' in the UK after an outbreak of the disease in the 1980s. Both diseases are caused by misfolded proteins called prions, which induce other proteins in the brain to clump, eventually destoying neurons. Humans are thought to contract the disease by consuming beef containing infected bovine brain or other central nervous system tissue. But it also spreads through blood transfusions, and some worry that the prion disease is transmitted via contaminated surgical instruments . The BSE outbreak in the 1980s and 1990s led to a surge in British vCJD cases, and a total of 177 have been detected in the UK to date, with just one in the last two years. Cases of vCJD peaked in 2000, leading some scientists to speculate that the disease takes about a decade to develop. Yet other studies of different forms of CJD suggest its incubation time could be much longer — indicating that many Britons may be carrying the infection without symtoms. Studies have come to varying conclusions as to just how many people harbour the abnormal prion protein (PrP) that causes vCJD. Surveys of tens of thousands of appendices and tonsil, discarded after surgery, have come up with prevalence rates ranging from 1 in 40001 to 1 in 10,0002 to 03. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 18795 - Posted: 10.16.2013

JoNel Aleccia NBC News A neurosurgery patient treated at a New Hampshire hospital this spring did have a rare brain disorder known as Creutzfeldt-Jakob Disease, health officials confirmed Friday. That means that 15 other people in three states may have been exposed to the invariably deadly infection through potentially tainted surgical equipment. Autopsy results came back positive for CJD from the National Prion Disease Pathology Surveillance Center and were reported to the New Hampshire Department of Health and Human Services and Catholic Medical Center, where the surgery took place. Earlier this month, New Hampshire officials notified eight patients who may have been exposed to CJD through shared equipment. Five others in Massachusetts and two in Connecticut were also warned of the risk, health officials in those states said. "Though we are not surprised by the test results, we are saddened by the toll this disease takes on families and our sympathies go out to all those affected," said Dr. Jose Montero, New Hampshire's director of public health, in a statement. The initial patient turned out to have sporadic CJD, which occurs spontaneously. It's not the variant form of the disease that causes a human type of "mad cow disease" and is associated with eating beef contaminated with the cattle version of the infection, called bovine spongiform encephalotpathy, or BSE, experts said. The problem arose because standard hospital disinfection techniques cannot eradicate the prion that causes CJD. A prion is a protein and the type that causes BSE and CJD is misfolded and somehow manages to transform other proteins into disease-causing shape.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 18678 - Posted: 09.21.2013

By Philip Yam New Hampshire health officials announced last week that hospitals in three New England states may have accidentally exposed 15 people to prions, the infectious protein that ravages the brain and leaves it full of holes. Evidently, the hospitals involved used surgical tools that had previously been deployed on a patient who officials suspect later died from a particular prion infection called sporadic Creutzfeldt-Jakob disease (CJD). As disturbing as the revelation was, it pales in comparison with the announcement in 2002, when the University of Pittsburgh Medical Center Presbyterian announced that up to 4,000 patients might have been exposed to the prion. Both incidents show that the hospital transmission of prion diseases remains an ever-present possibility, if thankfully a very unlikely one. Prions are unusual pathogens distinct from parasites, fungi, bacteria and viruses. They are misfolded proteins that can transform healthy proteins into sickly versions, leading to the death of cells. Particularly abundant in the brain, they took center stage in the late 1980s, during the mad cow outbreak in the U.K. People who ate beef from infected cows ran the risk of contracting a variant of CJD. The panic brought to light the range of prion diseases that can affect humans and animals, including one that develops spontaneously. Called sporadic CJD, this spontaneous form strikes about one in every million people each year for no apparent reason. What’s more, the brain tissue from the unlucky few can infect healthy brains—hence, the worry over surgical transmission. © 2013 Scientific American

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 18643 - Posted: 09.14.2013

Mo Costandi Prions are best known as the infectious agents that cause ‘mad cow’ disease and the human versions of it, such as variant Creutzfeldt–Jakob Disease. But the proteins also have at least one known useful function, in the cells that insulate nerves, and are suspected to have more. Now researchers have provided the first direct evidence that the proteins play an important role in neurons themselves. The team reports in the Journal of Neuroscience1 that prions are involved in developmental plasticity, the process by which the structure and function of neurons in the growing brain is shaped by experience. Prions come in two main forms: the normal version and the misfolded, infectious version. The normal version, known as cellular prion protein (or PrPC), is present in every cell of the body and helps to maintain the myelin sheath in the cells that protect the nerves2. But the molecule is abundant in neurons themselves, especially during development. Because it is tethered to the membrane, it is widely assumed to be involved in signalling between nerve cells, but little direct evidence has been found for this. Neurobiologist Enrico Cherubini of the International School for Advanced Studies in Trieste, Italy, and his colleagues therefore decided to look at the effects of electrical stimulation on slices of tissue from the hippocampus of healthy 3–7-day-old mice and of animals genetically engineered to lack the gene that encodes the prion protein. They used electrodes to stimulate individual cells at the same time as the networks of young neurons showed bursts of spontaneous electrical activity, or to simultaneously stimulate pairs of cells that are connected to each other. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 13: Memory, Learning, and Development
Link ID: 17809 - Posted: 02.16.2013

by Jessica Hamzelou COULD we stem the tide of ageing by delaying the deterioration of stem cells? A new compound that appears to do just that could help us find ways to protect our organs from age-related wear and tear, experiments in mice suggest. As we age, so do our mesenchymal stem cells (MSCs): their numbers in our bone marrow decline, and those that are left lose the ability to differentiate into the distinct cell types - such as bone, cartilage, fat and possibly muscle cells - that help in the healing process. "We think this ageing of stem cells may be linked to the onset of some age-related disorders, such as osteoporosis," says Ilaria Bellantuono at the University of Sheffield in the UK. Earlier research in mice had suggested that the prion protein expressed by MSCs might play a role in holding back stem cell ageing. Mice lacking the prion protein were less able to regenerate blood cells. The study provided more evidence that correctly folded prions serve a useful purpose in the body, despite the role that misfolded prions play in BSE and vCJD. Bellantuono and her colleagues have now found that the prion protein performs a similar function in humans - older MSCs from human bone marrow expressed less of the protein than younger ones. In a bid to find a compound that might slow MSC ageing, the team tested numerous molecules known to target prion proteins on dishes of human stem cells. One molecule emerged as a potential candidate - stem cells treated with it produced 300 times the number of cells over 250 days than untreated stem cells. The treated cells kept on dividing for longer. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 13: Memory, Learning, and Development
Link ID: 17175 - Posted: 08.18.2012

By James Gallagher Health and science reporter, BBC News The tantalising prospect of treating a range of brain diseases, such as Alzheimer's and Parkinson's, all with the same drug, has been raised by UK researchers. In a study, published in Nature, they prevented brain cells dying in mice with prion disease. It is hoped the same method for preventing brain cell death could apply in other diseases. The findings are at an early stage, but have been heralded as "fascinating". Many neuro-degenerative diseases result in the build-up of proteins which are not put together correctly - known as misfolded proteins. This happens in Alzheimer's, Parkinson's and Huntington's as well as in prion diseases, such as the human form of mad cow disease. Turn off Researchers at the University of Leicester uncovered how the build-up of proteins in mice with prion disease resulted in brain cells dying. They showed that as misfolded protein levels rise in the brain, cells respond by trying to shut down the production of all new proteins. It is the same trick cells use when infected with a virus. Stopping production of proteins stops the virus spreading. However, shutting down the factory for a long period of time ends up killing the brain cells as they do not produce the proteins they actually need to function. BBC © 2012

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 5: The Sensorimotor System
Link ID: 16759 - Posted: 05.07.2012

by Helen Thompson Reports of ‘mad cow’ disease in the United States erupted in the news this week after the US Department of Agriculture (USDA) confirmed that the remains of a California dairy cow had tested positive for bovine spongiform encephalopathy (BSE). This marks the fourth case of BSE identified in the US, and the first case in six years. In spongiform encephalopathy diseases, abnormally folded prion proteins accumulate in the brain, causing other proteins to deform as well. BSE has proved to be unusually adept at jumping between species; humans exposed to BSE can develop its human counterpart: Creutzfeldt-Jakob disease (CJD). In a statement released on 24 April, Karen Ross, Secretary of the California Department of Food and Agriculture said, “The detection of BSE shows that the surveillance program in place in California and around the country is working.” Food safety advocates such as Yonkers, New York, -based Consumers Union say it’s a warning sign that surveillance is inadequate and needs to be stepped up. Ross’s statement also makes a point of noting a key feature of this particular case: The infected cow carried what is known as ‘L-type’ BSE, a version of the disease that has not been detected before in the US and has so far not been associated with transmission through animal feed. As the policy debate over testing rumbles on, here is a short guide to what is known and not known about this rare strain and its unexpected appearance. © 2012 Nature Publishing Group,

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 16740 - Posted: 05.02.2012

By STEPHANIE STROM The Department of Agriculture announced that it had identified a case of mad cow disease, the first in six years, in a dairy cow in central California. The cow “was never presented for human consumption, so it at no time presented a risk to the food supply or human health,” John Clifford, chief veterinary officer at the department, said in a statement. Dr. Clifford noted that milk did not transmit bovine spongiform encephalopathy, the scientific name for mad cow disease. He expressed confidence in the health of the nation’s cattle and the safety of beef during a press briefing in Washington. The animal had been picked up from the farm and taken to a rendering plant, which noticed some of the signs of B.S.E., such as unsteadiness and aggression, and notified U.S.D.A. inspectors, Dr. Clifford said in a brief interview. The body will remain at the rendering facility and will be disposed of once the agency completes its investigation, probably by incineration or some other method that ensures the destruction of its tissues. It was the fourth reported case of mad cow disease, a degenerative disease that affects the brains and spinal cords of cattle, in the United States. Humans can contract the disease by eating meat from an infected cow. Only one case of mad cow disease in the United States was of the type derived from feed. That case set off a panic in 2003 when a Canadian-born cow in Washington state tested positive. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 16708 - Posted: 04.25.2012

Bijal P. Trivedi On a frigid winter's morning in 1992, Susan Lindquist, then a biologist at the University of Chicago in Illinois, trudged through the snow to the campus's intellectual-property office to share an unconventional idea for a cancer drug. A protein that she had been working on, Hsp90, guides misfolded proteins into their proper conformation. But it also applies its talents to misfolded mutant proteins in tumour cells, activating them and helping cancer to advance. Lindquist suspected that blocking Hsp90 would thwart the disease. The intellectual-property project manager she met with disagreed, calling Lindquist's idea “ridiculous” because it stemmed from experiments in yeast. His “sneering tone”, she says, left an indelible mark. “It was actually one of the most insulting conversations I've had in my professional life.” It led her to abandon her cancer research on Hsp90 for a decade. Today, more than a dozen drug companies are developing inhibitors of the protein as cancer treatments. Lindquist seems able to shrug off such injustices, now. Her work over the past 20 years has consistently challenged standard thinking on evolution, inheritance and the humble yeast. She has helped to show how misfolded infectious proteins called prions can override the rules of inheritance in yeast, and how this can be used to model human disease. She has also proposed a mechanism by which organisms can unleash hidden variation and evolve by leaps and bounds. She was the first female director of the prestigious Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, and has received more than a dozen awards and honours in the past five years. In a paper being published this week in Nature, she and her colleagues show that in wild yeast, prions provide tangible advantages, such as survival in harsh conditions and drug resistance1. © 2012 Nature Publishing Group

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 16388 - Posted: 02.16.2012

By Rebecca Cheung The protein-based pathogens known as prions may pass between different species more easily than has been thought, a team of French researchers reports in the Jan. 27 Science. By infecting engineered mice with prions from cows and goats, scientists also have shown that the invaders readily target tissues other than the brain. “We may underestimate the threat posed by some of these diseases by focusing only on the brain,” says Pierluigi Gambetti, a prion researcher at Case Western Reserve University in Cleveland. “It adds a new element to the equation.” The research also raises the possibility that new prion strains recently identified in cattle and small rodents might be able to jump to other species, including humans. “We should, in the future, be more exhaustive when looking at the possibility of prions being passed from one species to another,” says Hubert Laude, a professor at the French National Institute for Agricultural Research in Jouy-en-Josas and a coauthor of the study. Prions closely resemble normal proteins made by a host. When prions invade a host, they propagate by forcing these normal host proteins, actually called prion proteins, to assemble improperly. When these malformed proteins accumulate in the brain, they cause mind-wasting conditions such as Creutzfeldt-Jakob disease in people and scrapie in sheep. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 16304 - Posted: 01.28.2012

By Tina Hesman Saey Infectious proteins that cause brain-wasting conditions like mad cow disease appear to build up in the brain long before initiating the cascade of deterioration that leads to dementia and death, a new study of mice finds. The findings suggest that other factors besides the misshapen infectious proteins characteristic of prion diseases may control the lethality of the disease. If scientists can determine what those factors are, future treatments may be able to prevent the infectious protein diseases — which include mad cow disease, scrapie in sheep and Creutzfeldt-Jakob disease in people — from progressing to a fatal stage. “We don’t know what’s going on here, but we do know there’s something interesting,” says John Collinge, director of the United Kingdom Medical Research Council Prion Unit in London, who headed the new study. Findings reported by Collinge and his colleagues in the Feb. 24 Nature contradict the idea that infectious versions of a normal brain protein called PrP accumulate slowly, gradually twisting all of the healthy copies of the protein into a disease-causing form. Researchers have thought that the disease-causing prions slowly build up to toxic levels that spell the death of brain cells. But the new study shows that the process is anything but gradual, and that infection and toxicity are independent stages of the disease. Prions quickly build up in the brains of mice over the course of a month or two, Collinge and his colleagues found, peaking at about 100 million infectious particles per brain. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 15052 - Posted: 02.26.2011

Tiffany O'Callaghan Invasive biopsy is currently the only sure way to diagnose the degenerative neurological condition Creutzfeldt–Jakob Disease (CJD). But a highly sensitive assay could change that, providing a fast, accurate alternative for early diagnosis of this rare but deadly condition. In its most common form, known as sporadic CJD, the disease affects roughly one in a million people. Beginning in the 1990s, several cases of a variation of CJD known as vCJD were reported among people who had consumed beef from cows infected with another disease, bovine spongiform encephalopathy (BSE). The findings, published online in Nature Medicine1, also suggest that the assay — developed by microbiologist Ryuichiro Atarashi of Nagasaki University, Japan, and his team — could pave the way for the screening of broad sectors of the population. CJD is a prion disease, in which an isomer of a common protein known as the prion protein (PrP) takes on an abnormal shape and becomes an infectious variant called PrPSc. This variant is thought to trigger the subsequent malformation of other PrP proteins. Unlike their normal counterparts, PrPSc prions cannot be broken down, and instead accumulate — often clustering in brain tissue. The pockets of abnormal tissue that result cause brain tissue to develop a sponge-like appearance, and because prion conditions can be spread by affected humans or animals, the diseases are often referred to as transmissible spongiform encephalopathies (TSEs). Humans can be affected by several such conditions, while in addition to BSE in cows, there are several other such disorders among animals, including a condition called scrapie in sheep and hamsters. © 2011 Nature Publishing Group,

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 14935 - Posted: 01.31.2011

by Debora MacKenzie You catch flu by inhaling germs – now it seems you can catch prion diseases that way too. Prions are misshapen proteins that cause brain degeneration in conditions such as mad cow disease and scrapie in animals, and Creutzfeldt–Jakob disease in humans. They can get into you if you eat infected meat or receive infected blood, but it was thought they couldn't spread through air. Now Adriano Aguzzi of the Swiss Federal Institute of Technology in Zurich reports that mice exposed for 10 minutes to aerosols containing as little as 2.5 per cent brain tissue from mice with scrapie all developed the disease within months. The prions didn't need processing by the immune system first, as some other research has suggested, but entered the brain directly through nasal nerves. "We were amazed at how efficiently they spread," says Aguzzi. He warns that this doesn't mean animals or people with prion diseases actually transmit them through the air: there have been no unexplained cases of disease transmission which suggested this. But workers in mills that process potentially infected carcasses may need more respiratory protection. Labs that test for prions routinely make 10 per cent suspensions of brain tissue, and any handling – pipetting, for example – creates aerosols. Prion labs are not required to use safety equipment that protects workers from aerosols. Aguzzi, who tested his aerosols at the highest level of protection, thinks those labs may now need to rethink safety measures. Journal reference: PLoS Pathogens, DOI: 10.1371/journal.ppat.1001257 © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 14873 - Posted: 01.15.2011

A fast test to diagnose fatal brain conditions such as mad cow disease in cattle and Creutzfeldt-Jakob disease in humans could be on the horizon, according to a new study from National Institutes of Health scientists. Researchers at NIH's National Institute of Allergy and Infectious Diseases (NIAID) have developed a highly sensitive and rapid new method to detect and measure infectious agents called prions that cause these diseases. Prion diseases are primarily brain-damaging conditions also known as transmissible spongiform encephalopathies. They are difficult to diagnose, untreatable and ultimately fatal. A key physical characteristic of these diseases is dead tissue that leaves sponge-like holes in the brain. Prion diseases include mad cow disease, or bovine spongiform encephalopathy in cattle; scrapie in sheep; Creutzfeldt-Jakob disease in humans; and chronic wasting disease in deer, elk and moose. For more information about NIAID research on prion diseases, visit the NIAID Prion Diseases portal (http://www.niaid.nih.gov/topics/prion/Pages/default.aspx). Currently available diagnostic tests lack the sensitivity, speed or quantitative capabilities required for many important applications in medicine, agriculture, wildlife biology and research. Because prion infections can be present for decades before disease symptoms appear, a better test might create the possibility for early treatment to stop the spread of disease and prevent death. Now, a blending of previous test concepts by the NIAID group has led to the development of a new prion detection method, called real time quaking induced conversion assay, or RT-QuIC. This approach is described in a paper now online in the open-access journal PLoS Pathogens. Byron Caughey, Ph.D., led the study at NIAID's Rocky Mountain Laboratories in Hamilton, Mont.

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 14737 - Posted: 12.04.2010