...| Prion Disease | VET 140 Mr. Bell | Roger Meadows 5/7/2012 | A prion is a protein that has been mutated. Prion means proteinaceous infectious particle. Proteinaceous infectious particle can be broken down into:” proteinaceous which is relating to, resembling, or being protein, Infectious which is capable of causing infection, and particle which is a minute quantity or fragment” (Merriam – Webster 2012). So a proteinaceous infectious partial would be a very small protein that can cause an infection. The protein called PrP can be found in nerve cells all through the brain. The prion does not have a nucleus like other infectious dieses, and this makes it rare. Without the nucleus, it is not a virus or bacteria; it is only a protein (Hinz, A., Doremus, C., 1997). Prions cause a wide range of neurologic diseases in sheep, cows, and humans and were identified by Stanley Prusiner at UCSF in 1981 (Immunity and Disease, 2001). Prions are responsible for transmissible spongiform encephalopathies or TSE’s. Spongiform encephalopathies can develop three different ways, either by a normal prion changing into an abnormal one, or the PRNP gene that targets the creation of a protein which mutates into an abnormal protein, or consumption of contaminated items (Hinz, A., Doremus, C., 1997). TSE’s are very rare and affect around one person in every million each year over the world. TSE’s include bovine spongiform encephalopathy, or mad cow disease in cattle, scrapie in sheep, chronic...
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...Ask and Answer Paper: Understanding Prions Ask and Answer Paper: Understanding Prions Steven English Ask and Answer Paper: Understanding Prions 1 As its name suggests, Pasteur's germ theory of disease simply states that microbes are the cause of disease. Though it seems obvious now, it was revolutionary at the time of its inception and is central to our modern understanding and treatment of diseases. It replaced the commonly held and relatively complex 'humoral theory' with a simpler concept that boiled down to a relationship between microorganism and host (“Germ Theory,” n.d.). But as our understanding of the disease process grows with more and more diseases continuing to be discovered, we find that while viruses and microorganisms might be the main cause they aren't the only way in which disease can spread. Prions are one such challenge to this simple germ-disease paradigm. In this paper, the following questions about prion diseases (focusing primarily on kuru and Creutzfeldt-Jakob disease) will be examined: “What are they and what does their discovery mean for our understanding of disease and evolution?” The prion protein (PrPC) is a protein seemingly found in the brains of almost all vertebrate animals which...
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...Prions What Are They? Prions are proteinaceous transmissible pathogens, and are believed to infect and propagate the conformational changes of the native proteins into the the abnormally structured form. They are often called Spongiform Encephalopathies due to the swelling of the brain, accompanied with the observation of vacuoles like structures. Different prions affect different regions of the brain • Cerebral cortex: the symptoms include loss of memory and mental acuity, also visual imparement (CJD). • Thalamus: Fatal Familial Insomnia (FFI). • Cerebellum: lose the control of body movements and difficulties to walk (kuru, GSS). • Brain stem: In the mad cow disease (BSE), the brain stem is affected. 3 Formation Of A Prion (in the cell) α-helix β-sheet Conformational change PrPSc Normal protein (folded structure) PrPC Aggregation Gain of toxic activity Loss of biological function Disease-associated protein (misfolded structure) PrPC The normal protein is called PrPC (for cellular) is a transmembrane glycoprotein (neurons, lymphocytes); its function is unknown; it binds Cu2+ (regulation its homeostasis) PrPSc The abnormal, disease-producing protein is called PrPSc (for scrapie) has the same amino acid sequence (primary structure) is monomeric and easily digested by proteases is multimeric and resistant to digestion by proteases When PrPSc comes in contact with PrPC, it converts the PrPC into more of itself These molecules bind to each...
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...Prion Disease BSE (bovine spongiform encephalopathy) also known as Prion Disease, is a disease many are still trying to understand as to why it happens. “Prion diseases or transmissible spongiform encephalopathies (TSEs) are a rare progressive neurodegenerative disorders that affect both human beings and animals” (Aguzzi, 2001). They are known to follow a long incubation period, along with substance like a spongiform changes related with loss of neuronal, and a lack to be able to show inflammatory response. The organism description, is the causative agents of TSEs are believed to be prions. “The term "prions" refers to abnormal, pathogenic agents that are transmissible and are able to induce abnormal folding of specific normal cellular proteins called prion proteins that are found and seen the most in the brain. The functions of these normal prion proteins are still not completely understood.”(Aguzzi, 2001) “The abnormal folding of the prion proteins leads to brain damage and the characteristic signs and symptoms of the disease. Prion diseases are usually rapidly progressive and always fatal. It is known that the likelihood of obtaining prion disease is by age. The older you are the more prone you are to it. Several mathematical models proposed over the past years predicted that the frequency of the disease would level off to zero around the turn of the century.”(Aguzzi, 2001) Most deaths occurred after being contaminated with this disease if usually one year after...
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...brain due to this disease which gives sponge like appearance in its tissue. These spongy holes causes the brain deterioration of the cows . BSE have 2.5 to 8 years of incubation period and it shows its sign in the case of adult animals at the age of 4 to 5 years. Many scientists refer the abnormal protein called prion as the cause for BSE. In the cattle's, the brain protein that is prion gets incorrectly folded up by itself. When this type of defective protein comes across other types of...
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...Aggregates/Nuclear inclusions: Villain or tragic hero? Introduction The major defining feature of neurodegenerative diseases is the progressive accumulation of nuclear inclusions comprising of irregularly folded protein aggregates. Previously it was thought that protein aggregation is the cause of neurodegeneration as it had been established that neurodegenerative diseases such Huntington’s disease (HD), Parkinson’s disease (PD), Alzheimer’s disease (AD), prion disease, and amyotrophic lateral sclerosis (ALS) all shared a common feature which was these aggregated proteins and the formation of inclusion bodies (Ross and Poirier, 2004). However, recent studies have suggested that protein aggregation may not be the cause of toxicity to cells but that it may in fact be a protective mechanism. The aggregates formed in the above-mentioned diseases can be a consequence of mutations in the sequence of the protein that is related to the disease, increased amounts of a normal protein due to a genetic variation, or even the absence of genetic variations. These may be initiated by environmental stress or aging (Ross and Margolis, 2005). The aggregated proteins can build up and form inclusion bodies, which can be either intracellular or extracellular. There is an ongoing debate about the role of aggregation in the disease process even though one of the most common pathological features of neurodegenerative disorders is inclusion bodies. There is much evidence indicating that aggregation...
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...What are Prions and their role? Prions are the proteins that cause Mad Cow Disease also known as BSE. Prions are an infectious protein. Prions are defined as an proteinaceous infectious particle, the protein is capable of changing the conformation of proteins to match its own and becomes infectious without the use of genetic materials. They can cross between species such as cattle, and sheep. Extreme heats chemical agents can inactivate the proteins. Prions are naturally occurring in the body and are not considered foreign nor do they stimulate the immune system and will not hurt your body, however the disease causing prions contact the normal prions by physical contact and alter the normal prions therefore causing the disease. With Mad Cow Disease The Prions target the specific protein in the cell that is normal called PrPC The role of protein Misfolding in BSE Diseased proteins result from improper folding and therefore the misfolded proteins induces copies of the same protein to also again misfold and increases the disease progress when it is misfolded. The scrapie prion PrPsc contacts and bumps into the normal cellular form PrPc intermediate and shifts the folding process converting them to the misfolded prion (the sheep version of mad cow disease called the PrPsc prion). The process continues over and over again. The body continues producing the normal cell PrPc and the scrapie prion PrPsc continues creating more replications of itself without needing any nucleic...
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...Scrapie is a specific type of prion which could cause a central nervous system disease among sheep and goats. Prion is a kind of abnormally folded protein which has “extreme resistance to ionizing and ultraviolet.” (Prusiner, 2) According to current researches, scrapie prions are converted from normal cellular PrP by changing some α-helices into β-sheets. This converting process would change the solubility of the protein and also prevent the protein from digested by proteases. Since researcher has invented techniques to transfer scrapie prions from sheep into mice, scrapie has become the prion people studied the most. As Prusiner mentions in his book, transgenetic studies in prion discovered that “PrPSC acts as a template upon which PrPC is...
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...groups of cysteine amino acids, also known as a disulfide bridge (strongest bond). Van der Waals forces interactions help in the stabilization of protein structure. These interactions refer to to the attractive and repulsive forces that occur between molecules that become polarized. These forces contribute to the bonding that occurs between molecules. (Borges,2014) Bovine Spongiform Encephalopathy Mad cow disease or bovine spongiform encephalopathy is a deadly neurological disease that affects adult cattle. It is transmitted from animal to animal through contaminated food that contain infected central nervous system and spinal cord remnants. The contaminated food contain prions, a type of misfolded protein. A healthy brain prion protein (PrP) Is converted into a diseased PrPSc. “All known prions induce the formation of an amyloid fold, in which the protein polymerises into an aggregate consisting of tightly packed beta sheets. Amyloid aggregates are fibrils, growing at their ends, and...
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...there are numerous ways to contract the disease. Thankfully, Creutzfeldt-Jakob is not common in today's times anymore. For every one million people in the world, only one will be affected every year (Creutzfeldt-Jakob Disease Fact Sheet, 2003.) Scientists have discovered that you can get CJD genetically, acquired, or sporadically (Creutzfeldt-Jakob Disease, 2017.) When people get CJD from their genetics, it means that their chromosome 20 gene is changing. The chromosome 20 gene is also known as the gene responsible for prion protein (Creutzfeldt-Jakob Disease, 2017.) The way that this gene changes in a person is because the mishap was passed down from their parent. This type of CJD usually occurs when the person is between 20 and 40 years old. Genetic CJD is held accountable for 10-15% of all cases (Creutzfeldt-Jakob Disease, 2017.) Another way people can get CJD is called “acquired.” This means the person came in contact with an outside source of an infected prion protein. Acquired CJD accounts for just 1% of all the people affected with the disease (Creutzfeldt-Jakob Disease, 2017.) The main ways a person would get acquired CJD is by medical procedures, meaning the doctor used a medical instrument that was infected or when you transplant human tissue, or eating meat infected with mad cow disease (Creutzfeldt-Jakob Disease, 2017.) Lastly, a person can get CJD sporadically. This means that when a person passes the age of 60, they can contract the disease for unknown reasons. Sporadic...
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...also known as Prions. Prions can form by changes in DNA or mutations which result in a change of protein conformation. Chaperones provide an environment so proteins fold properly, bad chaperones influence the good chaperones to take form as harmful proteins. Eventually aggregates of these harmful proteins form and these aggregates lead to cell death. “The prion hypothesis suggest that diseases like BSE are caused by the misfolding of a protein known as PrP that most cells contain. Once a few copies of protein become misfolded they cause PrP’s to misfold, leading to accumulation of insoluble proteins in the cell. These misfolded proteins cause cell death and damage to the nervous system.” A country without regulations in place can help reduce risk of transmitting BSE by properly discarding possibly contaminated cattle feed. Brain and spinal cord matter should be discarded, and watching cattle with possible signs of BSE should not be introduced into the feed. One possible sign of BSE in cattle is not being able to walk, some may demonstrate aggressive behavior. The following statement is another possible way of introducing safe ways to discard contaminated cattle in a country without regulations: “According to Dr. Lisa Ferguson, a senior staff veterinarian at the Agriculture Department, said the department favored dissolving carcasses in tissue digestors, are essentially giant pressure cookers heated to 300 Fahrenheit.” This process is said to destroy the prions and reducing the...
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...Corn Fed vs. Grass Fed Have you noticed how there’s an increasingly wider selection of types of beef to be purchased? Which option is healthier? Which one is least expensive? There has been an ongoing dispute over which choice of beef we should be consuming. While both may seem to have their own advantage and disadvantage; ranging from being cost-efficient, to more beneficial nutrients. Both contribute to the eco-system, but in completely different ways. While grass-fed beef is the healthier alternative, it can prove to be a bit pricey, nonetheless, grass-fed beef provide us with more nutrients; they’re higher in Omega-3 fatty acid and vitamin E. Corn-fed beef, on the other hand, is relatively more affordable. The million dollar question should be, it’s affordable, but at what cost? What makes corn-fed beef so much cheaper than grass-fed? Corn-fed cattle go through a process, almost like an assembly line. The first step, the cow and calf live in a cow-calf operation. Here, the cow is artificially inseminated for the sole purpose of reproduction. For the first 6 months, the calf stays with their mother, once they’re old enough they’re taken to a pen, where they’re introduced to corn. To make a long story short, the calf is finally moved into a CAFO (confined animal feeding operation). From this point on, they’re all confined to small caged in areas. These facilities house hundreds, even thousands of farm animals. From this point on their diet is strictly corn, protein, vitamins...
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...Neurodegenerative Disorders: Alzheimer’s Disease 1. Amyloid Precursor Protein (APP) Alzheimer’s disease (AD) remains a major cause of senile dementia, which is characterised by an impairment of neuronal and synaptic function in addition to the accumulation of β-amyloid plaque and formation of neurofibrillary tangles within distinct portions of the brain (De Strooper and Annaert, 2000). Progression of this distinct pathology of neurodegeneration does not typically vary from patient to patient, beginning in cerebral cortex before targeting the hippocampus, neocortex as well as the sub-cortical nuclei (Braak and Braak, 1995). The role of amyloid precursor protein (APP) in the pathogenesis of Alzheimer’s disease is pivotal. The cleavage of APP by the proteases β and γ- secretase releases β-amyloid (Aβ) peptides which results in aggregation of the peptides due to misfolding to form fibrils of Aβ which comprise the key components of amyloid plaque deposits in the brains of AD patients (Glenner and Wong, 1984). Amyloid precursor protein (APP) is a trans-membrane glycoprotein which normally functions in synapse formation as well as axonal elongation. The protein possesses a small cytoplasmic domain but is composed primarily of a large extracellular domain. Processing of APP in the extracellular domain by α or β- secretase results in the complete removal of the protein’s ectodomain which gives rise to an accumulation of sizeable and soluble derivatives of APP referred to as...
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...Hydrophobic interactions are created from certain non-polar hydrophobic amino acids that move to the center of the protein and away from the watery medium. This results in twists or folds of the polypeptide chain. Toole, G., & Toole, S. 2004, p. 38. Essential As Biology for OCR ( ed.). Cheltenham, United Kingdom : Nelson Thornes Ltd. F. Bovine spongiform encephalopathy (BSE) at a molecular level. Part F-Disease at the Molecular Level * Bovine spongiform encephalopathy (BSE) is an infectious disease that is known as Mad Cow Disease. * The disease is primarily transmitted to cattle by consumption of meat and bone meal (MBM) contaminated with an infectious protein named prion (PrPSc). * Animals infected with the prion are sometimes sacrificed and used as fed propagating further BSE. Part F1-Role of Misfolding and Aggregation * Misfolding is the...
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...which is nonpolar. These R groups will cluster together on the interior of the protein and this will minimize their contact with water. The last one is van der Waals interactions takes place between the tightly packed nonpolar R groups on the interior of the protein. I would like to talk about BSE or bovine spongiform encephalopathy, in other words mad cow disease. This disease is called by misfolding prions at the molecular level. There are harmful and nonharmful forms of prions. The nonharmful form is PrPc and the harmful form is PrPsc. The PrPsc are hydrophobic and will cause the normal proteins to conform to their misfolding and harmful prion shape. This happens by way of a chaperonin. A polypeptide chain will enter the chaperonin and with proper environment of chaperonin, the polypeptide chain will fold correctly and exit as the normal prion, PrPc. Now in BSE, a polypeptide chain will enter into a “bad” chaperonin, the prion, and will get a misfolded prion to exit, PrPsc. The PrPsc will start to influence the normal proteins and in turn cause them to take the harmful prion shapes. The PrPsc will accumulate on the cell membrane and form fibers which will cause the cell to die. Now in countries that do not have regulations in place, to decrease the risk of BSE infecting their food source, you could not feed any animal remains to cattle. You could also...
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