The Bright Side of the Prions

        Prions, the proteins responsible for diseases like Creutzfeldt-Jakob (CJD) disease, have been becoming more and more ubiquitous in transplant recipients over the past couple of years. Prions, which are sometime referred to as proteinacious infectious particles, are misfolded protein molecules that can spread by causing other proteins to fold upon coming into contact. Scientist have studied these infectious protein molecule for sometime now, however, it was Carleton Gajdusek who originally discovered that, unlike other proteins, Prions lack the nucleic acid building blocks that are normally present in normal protein molecules. A little refresher about the structure and formations of proteins might be beneficial before continuing. As most of us already know, proteins consist of hundreds of amino acids that form long polymers chains. These long polymer chains give rise to an enormous amount of structural and functional variety. Despite their diversity, all protein molecules start with the basic amino acid sub-unit building blocks that makeup a polypeptide chain. The primary structure of a polypeptide chain undergoes a series of folding processes that eventually results in either secondary (α helix and the β pleated sheets), tertiary or quarternary structures. These long polymer chains fold into three dimensional polypeptide chains through hydrogen bonding, however, sometimes protein chains misfold during this process. Misfloded proteins are usually deactivated when this happens but when they remain active they can mutate and form Prions. According to an article posted on the NCBI website, Prions can survive in heat up to 200 °C for a couple of hours and adhere to stainless steel within minutes and remain infectious for long periods of time. The fact that Prions can survive such thorough decontamination processes means that they're easy to pass onto others. In addition to this, Prions are toxic and can cause neurodegenerative diseases but whats worse is that they're extremely resistant to disinfectants and sterilization methods. 
      This brings us to a recent concern surrounding the spread of Prions through infected organ donors. According to an article in Scientific American there is a growing epidemic of infected donors that are passing down infectious proteins. Apparently, the proteinacious infected particles have been identified in the corneas of donors who transmitted the disease on a number of occasions. According to a study posted in the scientific journal mBIO, researchers found that prion infected individual's corneas were riddled with infectious particles way before they ever exhibited symptoms. The presence of these prions found on the surface of the eye were caused by the weakening of the cornea, which allowed the infectious particles to exit through tiny neural conduits. This fortuitous observation has given doctors a way to screen for the hard to diagnose infection through methods such as electroretinograms. Because cornea transplants are becoming increasingly popular ( According to Scientific American 64,000 cornea transplants are performed each year in the US) this breakthrough arrived at a critical time and can be instrumental in developing preventative measures that stop this growing epidemic.   

Alzheimer's May Have Been Transmitted via Human Growth Hormone

Alzheimer's is a form of dementia that affects memory, thinking, and behavior. The human brain is composed of neurons, nerves, and many connection networks. Together, all of these parts of the brain work together like a factory. Alzheimer's prohibits the brain from acting and performing in this systematic and connected way.  Symptoms of this disease start with memory loss and confusion, and later lead to disorientation, changes in mood and behavior, unfounded suspiscions about family and friends, difficulty speaking, swallowing, and walking.

There is question as to whether there is a connection between human growth hormone and Alzheimer's transmission between humans.  Professor John Collinge noticed the relative connection as he extracted growth hormone from the pituitary gland of eight deceased patients; all of which had injected growth hormone as a child. It was found that all eight patients had contracted Creutzfeldt-Jakob Disease (CJD) via the hormone and died.  It was confirmed that none of the patients were carriers of known genes for Alzheimer's.  However, autopsies revealed that six of the eight patients had amyloid plaques, which are seen in patients with Alzheimer's.  To rule out the idea that CJD had a connection to amyloid proteins, a study was done on 116 deceased patients that died of CJD, but did not receive growth hormone. None of the deceased patients with CJD had any signs of the amyloid protein.  This meant that there was no connection between having CJD and amyloid proteins.  There was also no presence of tau tangles (proteins that are indicators of Alzheimer's).  However, researchers found that in people who died of Alzheimer's, there was presence of amyloid proteins. 

In my opinion, I believe there is an underlying connection between Alzheimer's and the human growth hormone.  In the article, it spoke of a study recently conducted that injected human amyloid brain material into the brains of mice.  This material remained dormant in the mouse's brain, but later on regained the ability to cause disease.  This shows that even though the amyloid protein remains inactive and basically "hides", it is still there and can cause disease later on in the organism's life.  I feel that this may be the case for humans.  For example in the case of the eight donors that had growth hormone extracted from their brains, they died of CJD which made it impossible to see if they contracted Alzheimer's later on in their lifetime.  Professor John Collinge definitely sparked a fire for Alzheimer's research to progress.