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PRIONS- An Infectious Life Without Genetic Material !
#1
Bug 
A Prion in the Scrapie form is an infectious agent which is composed of protein in a misfolded form. This definition always remain a topic of debate as this is a hypothesis on prion and many different forms of such protein have been identified recently very similar to so called Prions.
Prions are contrast to all other known infectious agenst like Virus, Bacteria, Fungus as these agents contains nucleic acids which may be either DNA or RNA or both. The word prion derived from word protein and infection. Prions word is coined in 1982 by Stanley Prusiner. Many of the Prion’s infections are untreatable and are fatal in nature. They are responsible for Creutzfeldt-Jakob disease in humans, in other mammals they develop transmissible spongiform encephalopathies, in cattles they are responsible for development of bovine spongiform encephalopathy BSE which is also commonly known as “mad cow disease”. The diseases due to prions are affecting structures of brain and neural tissue.
The propagation of prions takes place by transmission of misfolded proteins state. When any prion enters a healthy organism, it converts existing properly folded proteins into the disease associated prion form by misfolding its protein state. This prion act as a template to further misfold proteins and convert them in to prion state. This triggers a chain reaction that produces large amount of the prion forms which is known as amvloid fold. This form of amvloid fold consists of tightly packed sheets which are known as beta sheets. Amyloid aggregates are fibrils, growing and replicates when two growing ends become four after breakage. The altered structure of protein which is prion are more stable and keeps on accumulating in infected tissue, thus damage tissue and cause cell death. This protein or prions are resistant to denaturation even with chemical and physical agents.

In 1997, Prusiner isolated the protein and was infectious agent mainly composed of protein. This isolated was a new breakthrough in prion research work, for this great contribution, Prusiner won the Nobel Prize in Physiology or Medicine.
The protein of prions is known as PrP. When they are found in healthy people, and in infectious state, they are material with different structure and are resistant to enzymes like proteases.

The replication of Prions is explained by two hypothetical models, the first one is known as Fibril model of prion propagation and the another one is known as Heterodimer model of prion propagation. The first model assume that the single PrPSC molecule binds to single PrPc molecule, this is further converted into PrPSc. The other model focuses on breakage of PrPc into PrPSC and further breakages into new seeds.
The formation of plaques also known as amyloid (aggregation of infectious protein) causes neurodegenerative disease by aggregating within the central nervous system. This disrupt normal tissue and are characterized by holes in the tissue. Such type of infections are characterized with absence of an inflammatory reaction. Once incubation period is over, the disease spreads rapidly and leads to damage of brain and death.
Such diseases are transmissible from one species to another. The Human Prion disease like Creutzfeldt-Jakob disease is believed to cause infections to cattle and is further transmitted through infected meat!

Sterilization of prions is very difficult as they are resistant to chemical agents, physical agents, and this is because their denaturation is difficult. Therefore the protein hydrolysis with caustic soda, bleach is generally done. There sterilization with steam is done by autoclaving them at 134 °C (274 °F) for 18 minutes. Another method of sterilization is to immerse in 1N NaoH and heat in a autoclave at 121 degree Celsius for 30 minutes. Or Immerse in 1N NaClO that is sodium hypochlorite for one hour.

Today the research on Prions is working to find out ways to cure such infections completely. The sophisticated use of modeling techniques and computer application in it is helping scientist to find out compounds to bind to cavity in the PrPc and stabilize the deformed proteins, decreasing the harmful effect of PrPs. Many work on antiprion antibodies capable of crossing the barrier of blood-brain and treating prions proteins has been successful and further studies will bring such products in market soon.

In 2011 , it was discovered to degrade prions by lichens. The way to diagnose prion disease including BSE and CJD is still practically difficult. The examination of brain using Immunohistochemical and Neurophathological method is only the way at present. The way ahead is developing techniques like amplification with novel method called surround optical fiber immunoassay and detecting amount of PrPsc in brain tissues.

Today, though the treatment for Prions is difficult but as always, it is possible for science to go at its roots and to develop a treatment which will completely cure infections of prions in simple ways !
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#2
Very interesting information!
I would like to learn about the research of these particles, which shows the trend over time. Have any researchers of prions dynamics in living organisms?
As you know, all biological systems can be described using S-similar curves:
Here you can read for periodic conditions about this case:
http://iopscience.iop.org/1758-5090/3/4/045006/
For continuous conditions I opened a special discussion before.
Can someone give me an answer?
In turn, I suggest our new presentation, if someone wants. Please,write me to smlk03@mail.ru
Also, I would like to invite everyone to vote on:
http://www.linkedin.com/groups/Fermenter...mr_4410338

B.r.,
Sergey
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PRIONS- An Infectious Life Without Genetic Material !00