Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
TITLE?? The central nervous system (CNS)-be efficient is composed of the spinal cord and brain. Humans have a CNS that is unable to recover and regenerate damaged nerve cells, also named neurons (Brosamle, et al., 2000).-too much info in this sentence (too efficient), only humans? Start simple…the cells that make up the CNS are not able to divide, therefore… This is caused by chemicals called proteoglycans that are released by neurons (Cafferty, et al., 2007).-Completely? This is the only cause? Proteoglycans are proteins that have multiple sugars attached to them, making them resemble a tangled mess a tangled mess? (Cafferty, et al., 2007; Krekoski, et al., 2001). Although they are meant to protect the cells, the proteoglycans’ complex structures make it hard for neurons to regenerate.-how do they protect the cells? Be specific. Tell the story. They encase the damaged cells and restrain them from growing through the “wall” of proteoglycans-is this about neurons not being able to grow or not being able to divide and replace ones that have died? Make this more clear in the beginning, which is meant to close the damaged site and prevent further injury.-prevent injury? How so? Though it is helpful, it also prevents further growth past this sealed site. Another molecule, myelin, also gets tangled around the cell, blocking it off from more space to grow into-awkward wording, rephrase (Brosamle, et al., 2000). Luckily-don’t say luckily, you don’t know this…, recent experiments have shown that regeneration is possible.-make sure the reader knows what regeneration means exactly By genetically altering, electrically stimulating, and exposing chemicals to cells, proteoglycan and myelin levels can be lowered.-Rephrase this sentence. It is not clear. These methods may possibly promote and guide neuronal regeneration (Al-Majed, et al., 2000; Cafferty, et al., 2007; Davies, et al., 1999).-Not bad, just make it more clear that neurons, when damaged, need to find their conncections again. You need to discuss what a neuron is in general…a wire and that they are connected to other wires etc… and that these connections, if lost, will need to be reformed. Give some analogies. Make it clear to the general audience. New research has shown that lowering proteoglycan and myelin levels can promote regeneration.-did you talk about myelin in this paragraph at all? Also, did you discuss what myelin is in the intro? Does it have the same function as the proteoglycans you are discussing in terms of preventing further damage? By reducing the number of proteoglycans around the cells, neurons should then be able to grow into the new available space. One way to achieve this is by genetically altering the DNA for specific enzymes-general audience will need clarification, which are molecules that can break proteoglycans-this sentence will not be clear to the general reader (Cafferty, et al., 2007; Krekoski, et al., 2001; Steinmetz, et al., 2005). DNA for this enzyme was taken from bacteria and implanted in mice.-for what enzyme? You said to alter the DNA…I am confused. These mice successfully produced chondroitinase ABC, the enzyme that breaks proteoglycans.-If you are going to give the name, you should give it when you first mention the enzyme. The sugars were taken off of the proteins, creating a less complex structureAgain, the reader will be confused. Be more general with your description (Cafferty, et al., 2007). Because the proteoglycans broke into shorter, smaller pieces, neurons were able to grow into more areas. Reductions of proteoglycans also allowed scars in the nerves to reform and completely fill in the damaged areas (Krekoski, et al., 2001).-you end the last two sentences with the same word…”areas”. – also, I do not understand this sentence Scar tissue forming is important to regeneration, because they-they? are the first stages of development of fully functional cells.-you will need a better explanation for this scaring Further aid, like that accomplished with chemicals such as zymosan, can create even better, clearer environments for the neurons (Steinmetz, et al., 2005).-say what? Did you just jump? You need a more clear transition. In these experiments, neurons altered to breakdown proteoglycans yielded results of recovery after injury.-no idea what this sentence is saying to me… why did you just throw the chemicals in quickly at the end after discussing enzymes the entire time? Another way to promote regeneration is lowering myelin levels around the cells.-This is repetitive from what you said in the intro. Myelin is a chemical released by neurons to encase themselves, acting like armor against the environment.-this is intro material However, the “armor” of myelin seals the cell inside.intro By lowering the amount of myelin, neurons can grow back into the open space.intro Lowering myelin levels can be done by using genetically altered viral enzymes or human anti-bodies (Brosamle, et al., 2000; Tang, et al., 2007).-you need to transition into this from the previous paragraph…in addition to proteglycan breakdown, scientists have also discovered… (something like this). The DNA of neurons are altered so that viral enzymes and human anti-bodies can be made and enhanced, respectively.-no idea what this means They are able to digest myelin, leaving little restraint on regeneration.-are they putting these genes into the cells? What are they doing? The reader is lost… In one study, the human IN1 antibody was used to break long chains of myelin around the neurons.-in humans? Injection? Resulting fragments of myelin could not encase the damaged neurons, allowing them to grow longer (Brosamle, et al., 2000).-more explanation, details please These severed nerves were able to grow out into damaged areas and reattach to other nerves.-nerves or neurons? Using genetically altered viruses that release certain enzymes that-repeated “that” facilitate growth is also possible.-enzymes that facilitate growth? How? Are these myelin breakdown enzymes? These were injected around neurons, so that their enzymes could be near the nerves.-neurons? Nerves? Look up the difference. The enzymes caused parts of neurons to break through and grow out of the myelin casing without any myelin covering them-without any myelin covering them? (Tang, et al., 2007). Without any myelin-repeated “without any myelin” holding the neurons back, they were able to branch out and connect with other neurons.-This is a repeat. Transition? Transplanting neurons and surrounding material from another source to the injured area has also been shown to promote regeneration.-how does this relate to the breaking down of myelin/proteoglycans. Reader is lost. Neurons from other nerves were surgically removed and placed into the damaged site.-in the same individual? Human? Details… In the new environment, the neurons grew and connected to pre-existing broken ones resulting in severed nerves being reconnected (Davies, et al., 1999).-was the person able to use these neurons effectively now? What is the outcome of this? The problem with this is that transplanted nerves grow and attach to any other nerve. In other words, the wrong nerves will regenerate into the wrong areas.-the wrong nerves? Or just the wrong attachments… Nerves that communicate with muscles may grow into the skin, while nerves that interact between the brain and skin may grow into muscle. Surprisingly, electrical stimulation has been shown to guide nerves during regeneration and allow them to function correctly. In this approach, nerves are continuously shocked with pulses of electricity. Any amount of stimulation caused nerves to extend and grow into the correct areas. With this treatment, sensory nerves grew toward the skin and motor nerves grew toward muscles successfully (Al-Majed, et al., 2000). – I have no idea what this paragraph has to do with proteoglycan breakdown. Your intro implied that this was the main point of the paper. All of these methods may aid large scale human CNS recovery; while on the other hand, they also have some disadvantages. By genetically altering the nerves, enzymes that break proteoglycans and myelin will continuously do so. Proteoglycans and myelin are needed by healthy neurons to protect themselves from injury. If too many are lost, the neurons will be extremely vulnerable and will not function correctly. The enzymes will have to be modified so that they can be deactivated/activated when needed. Transplanting neurons from other hosts may also lead to the rejection of these nerve cells. The body may misjudge them as foreign invaders and attack them. Even if the neurons are taken from the same host, the surgery to remove them will cause another area of the body to be damaged. Electrical stimulation may also cause further damage. If your hands are shocked by static, you feel pain (your response to damage). This creates the possibility that prolonged electrical shock may injure other neurons. Despite the setbacks, these new treatments for neuronal regeneration are a huge step for researchers. They will soon be able to “cure” people with damaged CNS’s and problems like memory loss, concussions, and paralysis. Word Count: 999 References: Al-Majed, A. A., Neumann, C. M., Brushart, T. M., & Gordon, T. (2000). Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration. Journal of Neuroscience, 20, 2602-2608. Brosamle, C., Huber, A. B., Fiedler, M., Skerra, A., & Schwab, M. E. (2000). Regeneration of lesioned corticospinal tract fibers in the adult rat induced by a recombinant, humanized IN-1 Antibody fragment. Journal of Neuroscience, 20, 8061-8068. Cafferty, W. B. J., Yang, S. H., Duffy, P. J., Li, S., & Strittmatter, S. M. (2007). Functional axonal regeneration through astrocytic scar genetically modified to digest chondroitin sulfate proteoglycans. Journal of Neuroscience, 27, 2176-2185. Davies, S. J. A., Goucher, D. R., Doller, C., & Silver, J. (1999). Robust regeneration of adult sensory axons degenerating white matter of the adult rat spinal cord. Journal of Neuroscience, 19, 5810-5822. Krekoski, C. A., Neubauer, D., Zuo, J., & Muir, D. (2001). Axonal regeneration into acellular nerve grafts is enhanced by degradation of chondroitin sulfate proteoglycan. Journal of Neuroscience, 21, 6206-6213. Steinmetz, M. P., Horn, K. P., Tom, V. J., Miller, J. H., Busch, S. A., Nair, D., Silver, D. J., & Silver, J. (2005). Chronic enhancement of the intrinsic growth capacity of sensory neurons combined with the degradation of inhibitory proteoglycans allows functional regeneration of sensory axons through the dorsal root entry zone in the mammalian spinal cord. (2005). Journal of Neuroscience, 25, 8066-8076. Tang, X. Q., Heron, P., Mashburn, C., & Smith, G. M. (2007). Targeting sensory axon regeneration in adult spinal cord. Journal of Neuroscience, 27, 6068-6078.