Sometimes a scientific discovery shakes the confidence of scientists, making them question whether they truly understand nature's ground rules. That's exactly what prions have done to scientists' understanding of the ground rules for infectiousdiseases. Prions cause diseases,but they aren't viruses or bacteria or fungi or parasites. They are simply proteins, and proteins were never thought to be infectious on their own. Organisms are infectious, proteins are not. Or, at least, they never used to be. Prions entered the public's consciousness during the mad cow epidemic that hitEngland in 1986. For decades, however, scientists had searched for unusual, atypical infectious agents that they suspected caused some puzzling diseases that could not be linked to any of the "regular" infectious organisms. One possibility was that slow viruses-viruses that spent decades wreaking havoc in their hosts-might be the culprits, and these putative viruses were not only leisurely about multiplying but also hard to isolate. Now researchers are coming around, although reluctantly, to accepting the shocking fact that naked proteins can be infectious.
Prions enter cells and apparently convert normal proteins found within the cells into prions just like themselves. The normal cell proteins have all the same
"parts" as the prions- specifically the same amino acid building blocks -but they fold differently. They are much like the toy "Transformers" that were around in the 1980s. They could change themselves in to be different shapes with nothing added and nothing subtracted.
Prions enter brain cells and there convert the normal cell protein PrPC to the prion form of the protein, called PrPSC. When normal cell proteins transform into prions, amino acids that are folded tightly into alpha helical structures relax into looser beta sheets. More and more PrPC molecules transform into PrPSC molecules, until eventually prions completely clog the infected brain cells. The cells misfire, work poorly, or don't work at all. In mad cow disease, for example, with their brain cells running amuck, the mad cows wobble and stagger and appear fearful -their "madness" is craziness, not anger. Sheep and goats with the disease scrapie, which is like mad cow disease, become so uncomfortable and itchy that they frantically rub up against anything they can, finally scraping off – hence, the name of the disease -most of their wool and hair.
Ultimately, infected prion-bloated brain cells die and release prions into the tissue. These prions then enter, infect, and destroy other brain cells. And, as clusters of cells die, the brain stops looking like a brain and starts looking more
cortex, the thinking part of the brain, id dead. The brain stem, the part of the
Keiger, D. (2010, June 2). Immortal Cells, Enduring Issues. Johns Hopkins Magazine. Retrieved from http://http://archive.magazine.jhu.edu/2010/06/immortal-cells-enduring-issues/
In the subsequent essay I will discuss and explain the relative function of the Prion protein. The Prion protein, also known as PrPC, ‘’is a membrane-anchored protein with two N-glycosylation sites and, although it is highly expressed in the nervous tissues, its physiological functions have yet to be well established’’ (Coordination Chemistry Reviews). PrPC/PrP is found in healthy brains in this form, and consists of 250 Amino Acids, yet after a simple misfolding in the secondary structure; this can alienate the PrP and forms PrPsc, which is the abnormal form of the Prion protein. The infectious agent PrPsc causes neuropathological changes in the brain, and instantly places the individual under the category of someone with the prion disease. PrPsc forms insoluble fibres and thus cannot be studied well using Nuclear Mass Resonance (NMR), and it is also more resistant to protease digestion. Furthermore, ‘’ The transmissible spongiform encephalopathies (TSEs) arise from conversion of the membrane-bound prion protein from PrPC to PrPSc, the latter being the scrapie form. Examples of the TSEs include mad cow disease, chronic wasting disease in deer and elk, scrapie in goats and sheep, and kuru and Creutzfeldt-Jakob disease in humans’’ (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904554/. 2014). The following diagram shows the conversion from PrPc to PrPsc:
develops when clumps of abnormal proteins grow in the brain. It grows and grows but at a slow pace , overtime they add up until the brain cells becomes damaged and die. If you are concerned that you or any family member might have some of the symptoms you should talk to your family doctor. The symptoms that you should pay attention to should be:
Nerve cell death and tissue throughout the brain is the most significant affect over time. Naturally by age twenty-five the brain starts to decrease in size. With Alzheimer’s, the amount decrease is extremely significant. The cortex begins to shrivel up which is the part of the brain required for planning, remembering, and thinking. The most noticeable shrinkage occurs in the hippocampus. The hippocampus is responsible for the formation of new memories, it is also located inside the cortex. Upon further inspection under microscope, tissue samples are observed and synapses and nerve cell count is severely decreased. Tangles, are also found which our twisted strands of another protein due to nerve cells dying and bunching together. Plaques and tangles are prime suspects in the death and tissue loss in the Alzheimer’s brain. Beta-amyloid is a chemical and is sticky which causes it to gradually build up into plaques. This chemical derives from a larger protein found in the nerve cells with fatty membranes. These tangles destroy a vital cell transport system made of proteins.
Some normal cells produce chemicals called enzymes that break down cells and tissues. The cells use the enzymes to attack invading bacteria and viruses. They also use them to break down and clear up damaged areas in the body. The damaged cells are cleared away so the body can replace them with new ones.
The brain stem is also able to carry out these actions even when someone is asleep. To fully understand how crucial the brain is to survival, one must understand the functions of the brain stem. Brain death occurs when brain cells, which cannot regenerate themselves, are injured or dead. This results in brain death as the brain becomes starved of oxygen. One can only be pronounced brain dead, by a neurologist and even then, a number of criteria must be met, some of these include; unresponsiveness to stimuli; no reflexes and an inability to breathe unaided by a machine (Goila and Pawar, 2009).
The cell having lost all its dendrites and nucleus soon disintegrates. entirely, vanishing into the body's waste disposal system. With the depletion of enough nerve material the brain actually shrinks, sometimes by as much as ten. percent5. The number of percent.
In 1906, Dr. Alois Alzheimer discovered a “peculiar disease”. Dr. Alzheimer was an expert in linking symptoms to microscopic brain changes. Dr. Alzheimer noticed changes in the brain tissue of Auguste D., a patient who had died of an unusual mental disease. Her symptoms ranged from memory loss to unpredictable behavior. Afte...
the cell processes. If cells are denied energy they will die. The second law of
When a cell in our body has become infected or has become cancerous it’s surface changes. This is how the immune system can tell good cells from bad ones (the markings on the surface.) Once a bad cell has been recognized our bodies sends cells to destroy the damaged cell and prevent the spread of whatever caused the damage in the first place. The next step our body takes is to have the affected cells start to produce interferons and other helpful substances. These help to fight off unwanted organisms, and also to warn other cells of the invaders and prepare them to resist them therefore preventing the spread of disease.
As the human body goes through different experiences, the brain grows, develops, and changes according to the environmental situations it has been exposed to. Some of these factors include drugs, stress, hormones, diets, and sensory stimuli. [1] Neuroplasticity can be defined as the ability of the nervous system to respond to natural and abnormal stimuli experienced by the human body. The nervous system then reorganizes the brain’s structure and changes some of its function to theoretically repair itself by forming new neurons. [2] Neuroplasticity can occur during and in response to many different situations that occur throughout life. Some examples of these situations are learning, diseases, and going through therapy after an injury.
Biology The brain consists of both neurons and glia cells. The neurons, which are cells housed in a cell body called a Soma, have branches which extend from them, referred to as dendrites. From these dendrites extend axons which send and receive impulses, ending at junction points called synapses. It is at these synapse points that the transfer of information takes place. At the heart of neuroplasticity is the idea of synaptic pruning.
"Patterns of activity in small, more primitive areas of the brain are recapitulated in larger, more advanced parts," Sutton says. "This means that nature did not have to develop new rules of operation for different levels of the brain from small clusters of cells to large systems."
In every cell within an organism, the most crucial question is to survive or to die. In life, cell death is required so as to allow normal function. Cell death can be either physiological or programmed, in a process known as apoptosis. Cells that undergo apoptosis generally produce a wide range of morphological changes. These changes include shrinkage of cell, membrane blebbing, chromatin condensation and nuclear fragmentation. Apoptosis occurs due to the presence of a family known as the caspases. Apoptotic cells are then cleared by phagocytosis in vivo, where phagocytes swallow up the dying cells and digest them. [1]