Dictionary.com | Meanings & Definitions of English Words (original) (raw)

noun

  1. any of several petrels of the genus Pachyptila, located in the oceans of the Southern Hemisphere and having serrated edges on the bill.

noun

  1. a tiny proteinaceous particle, likened to viruses and viroids, but having no genetic component, thought to be an infectious agent in bovine spongiform encephalopathy, Creutzfeldt-Jakob disease, and similar encephalopathies.

/ ˈpriːɒn /

noun

  1. a protein in the brain, an abnormal form of which is thought to be the transmissable agent responsible for certain spongiform encephalopathies, such as BSE, scrapie, Creutzfeldt-Jakob disease, and kuru

/ ˈpraɪən /

noun

  1. any of various dovelike petrels of the genus Pachyptila of the southern oceans that have a serrated bill

/ prē′ŏn,prī′- /

  1. A particle of protein that is thought to be able to self-replicate and to be the agent of infection in a variety of diseases of the nervous system, such as mad cow disease. Prion replication (in which strings of amino acids are reproduced) stands as an exception to a central tenet of biology stating that only nucleic acids, such as DNA, can self-replicate. The mechanism of prion replication is not clearly understood.

  2. A protein
    that not only folds into an unusual shape itself, but also seems to have the ability to cause other proteins to change their shape as well. For a long time, scientists were skeptical that prions existed, but now most accept them.

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Word History and Origins

Origin of prion1

1840–50;

< New Latin < Greek príōn a saw

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Word History and Origins

Origin of prion1

C20: altered from pro ( teinaceous ) in ( fectious particle )

Origin of prion2

C19: New Latin, from Greek priōn a saw

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A Closer Look

In 1997 Stanley Prusiner was awarded the Nobel Prize for physiology or medicine for his theory that a deviant form of a harmless protein could be an infectious agent, a transmitter of disease. Named prions (short for proteinaceous infectious particle), these misshapen proteins cause healthy proteins to misfold, fatally clumping together in the brain. Unlike other disease-causing agents, prions lack genetic material (DNA and RNA). Neurodegenerative prion diseases are often called spongiform encephalopathies because they leave the brain riddled with holes like a sponge. In animals, prion diseases include scrapie in sheep and bovine spongiform encephalopathy, commonly known as mad cow disease in cattle. In humans, diseases such as kuru and Creutzfeldt-Jakob disease (CJD) are also thought to be caused by prions. All the diseases are characterized by loss of motor control, dementia, paralysis, and eventual death due to massive destruction of brain tissue. Humans are thought to contract prion disease most commonly by eating prion-contaminated flesh. Kuru, a rare and fatal brain disorder, brought prion disease to the forefront. First described in the 1950s, kuru was most common among the Fore people of Papua New Guinea, who had a custom of eating the brains of their dead during funeral feasts. It is speculated that a tribe member developed CJD, his or her contaminated brain tissue was ingested, and the disease spread. Kuru reached epidemic levels in the 1960s, but the disease declined after the government discouraged the practice of cannibalism and now it has almost completely disappeared.

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Example Sentences

According to the researchers, prion diseases have enormous public health implications from the safety of the blood supply to the proper decontamination of surgical tools used in neurosurgery.

The disease, which is caused by folded proteins known as prions, can transfer to people who eat the meat of infected cattle.

CJD is the most prominent of the handful of diseases, all fatal, that result when prions, proteins of uncertain function that are abundant in the brain, misfold into an infective form that spreads widely.

Gibison says while there is no evidence CWD can spread to humans, there is concern this could change, as other prion diseases -- such as Mad Cow Disease -- can spread through the consumption of infected meat.

However, the exact mechanisms by which disease-associated prion proteins trigger the death of nerve cells are only partially understood.