"The Kuru Disease"
"Last Recordings Before My Suicide - 2008" -
Kuru, or Creutzfeldt-Jakob disease (CJD), is a very rare and incurable degenerative neurological disorder (brain disease) that is ultimately fatal. Among the types of transmissible spongiform encephalopathy found in humans, it is the most common.
Transmissible spongiform encephalopathy diseases are caused by prions. The diseases are thus sometimes called prion diseases. Other prion diseases include Gerstmann-Sträussler-Scheinker syndrome (GSS), fatal familial insomnia (FFI) and kuru in humans, as well as bovine spongiform encephalopathy (BSE) commonly known as mad cow disease, chronic wasting disease (CWD) in elk and deer, and scrapie in sheep.
The prion that is believed to cause Creutzfeldt-Jakob exhibits at least two stable conformations. One, the native state, is water-soluble and present in healthy cells. As of 2007, its biological function is presumably in transmembrane transport or signaling. The other conformational state is very poorly water-soluble and readily forms protein aggregates.
People can also acquire CJD genetically through a mutation of the gene that codes for the prion protein(PRNP). This only occurs in 5-10% of all CJD cases.
The CJD prion is dangerous because it promotes refolding of native proteins into the diseased state. The number of misfolded protein molecules will increase exponentially, and the process leads to a large quantity of insoluble prions in affected cells. This mass of misfolded proteins disrupts cell function and causes cell death. Mutations in the gene for the prion protein can cause a misfolding of the dominantly alpha helical regions into beta pleated sheets. This change in conformation disables the ability of the protein to undergo digestion. Once the prion is transmitted, the defective proteins invade the brain and are produced in a self-sustaining feedback loop, causing exponential spread of the prion, death within a few months, although a few patients have been known to live as long as two years.
Stanley B. Prusiner was awarded the Nobel Prize in physiology or medicine in 1997 for his discovery of prions. For more than a decade, Yale University neuropathologist Laura Manuelidis has been challenging this explanation for the disease. In January 2007 she and her colleagues published an article in the Proceedings of the National Academy of Science and reported that they have found a virus-like particle (but without finding nucleic acids so far) in less than 10% of the cells a scrapie-infected cell line and in a mouse cell line infected by a human CJD agent.
The first symptom of CJD is rapidly progressive dementia, leading to memory loss, personality changes, inappropriate and unmotivated laughter, and hallucinations. This is accompanied by physical problems such as speech impairment, jerky movements (myoclonus), balance and coordination dysfunction (ataxia), changes in gait, rigid posture, and seizures. The duration of the disease varies greatly, but sporadic (non-inherited) CJD can be fatal within months or even weeks. In some people, the symptoms can continue for years. In most patients, these symptoms are followed by involuntary movements and the appearance of a typical diagnostic electroencephalogram tracing.
The symptoms of CJD are caused by the progressive death of the brain's nerve cells, which is associated with the build-up of abnormal prion proteins. When brain tissue from a CJD patient is examined under a microscope, many tiny holes can be seen where whole areas of nerve cells have died. The word 'spongiform' in 'transmissible spongiform encephalopathies' refers to the 'spongy' appearance of the brain tissue. [Emotions may switch suddenly from sadness to happiness with sudden outbursts of laughter. People with kuru become demented and eventually placid, unable to speak, and unresponsive to their surroundings. Most people die about 3 to 24 months after symptoms appear, usually as a result of pneumonia or infection due to bedsores (pressure sores).]