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Protein Gel Quickly Stops Bleeding
Stefan vd Linden writes, "An international team of scientists has discovered a substance to heal bleeding wounds within seconds. They're using a solution of protein molecules that self-organizes into a biodegradable gel. Until now they've only tested it on animals, but the tests were highly successful. From the article: 'Some surgeons are already excited about the material. "I see great potential in the eye field, the gastro-intestinal field, and in neurosurgery," says Dimitri Azar, head of ophthalmology at the University of Illinois at Chicago, US. "In the eye, even a drop of blood will blur your vision for a long time," Azar adds. "A material that would stop the bleeding could lead to a paradigm shift in how we practice surgery in the eye."'"
Well, unless my Google search fails me (no, I'm not a native English speaker, and I didn't know what platelets are), platelets are cells. As such, calling them "protein gel" is quite a stretch, since there happens to be more than proteins inside them. Besides, the idea is to stop bleeding quickly, and platelets aren't that fast.
A large percentage (which I don't have the time to look up right now) of battlefield deaths are really bleeding to death, not instantaneous. To this end, soldiers carry "Quckclot", a powder that is similar to this product- similar but not the same. This seems to work faster- and would save lives on the battlefield.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
There's several different kinds of hemophilia. Besides the genetic caused ones (usually platelets will be scarce, nonfunctional or both), lack of certain elements in food intake (see vitamin K) will affect bleeding.
me too, its called Bacta http://www.reference.com/browse/wiki/List_of_Star_ Wars_substances
Hemophilia can be caused by a lack of several proteins that take part in the clotting cascade, but the substance usually responsible is factor VIII.
The proteins they use are structurally very similar to natural silk, which is composed of proteins arranged primarily in a beta-sheet conformation. This conformation lines up strands of amino acids in a rough plane and cross-links them, usually with hydrogen bonds, but sometimes with ionic attractions or hydrophobic interactions.
The use of spider silk for clotting wounds has been known since ancient times; coagulation basically requires the onsite formation of a sticky, fibrous protein mess, and spider silk is almost completely sticky, fibrous protein (and unlike many similar foreign substances, doesn't provoke a dangerous immune reaction). This protein gel is basically the same sort of thing, but with the neat added trick that the cross-links are the result of ionic interactions, so that you could have an anhydrous powder of this stuff that you sprinkle onto a wound, and when it contacts electrolyte-rich bodily fluid (their paper on peptide nanofiber nerve scaffold notes it only requires normal physiological concentrations of salt, like those in saline or spinal fluid- from the news article, that's not especially clear), it turns to a fibrous gel.
As far as whether it promotes healing, interestingly enough, clotting itself promotes healing- the clot itself stimulates the cells in charge of repair- really, the sooner a stable clot is formed, the sooner your own cells can start fixing the damage. In the neural scaffold paper, the group also points out that, being composed of just the same amino acids ubiquitous in the body, the scaffold can be safely broken down to amino acids and then metabolized or excreted; I would imagine the same would be possible for the clotting gel when it is no longer needed.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
Here is the original press release:
l
http://web.mit.edu/newsoffice/2006/hemostasis.htm
Not much new information here, but it's nice to read things that come "straight from the horse's mouth", so to speak.
Of real consequence is the main researcher's lab website:
http://web.mit.edu/lms/www/
It is chock full of interesting research on self-assembling peptides, including what substances they've been trying, and the eternally-asked question, Can I run my laptop off of spinach?(They isolated the chloroplast/photosystem of spinach, and hope to use it for photovoltaic purposes).
As far as discussion, most of the application has been suggested in the field of delicate microsurgery. Why not band-aids for the masses? Most likely due to the cost. Aside from the financial barriers in bringing an idea to mass-market, especially in the medical field, imagine trying to keep the candidate liquid substance stable for storage, to be used at a moment's notice; if it self-assembles easily, then it can "gel up" just as easily, too. This is combined with the fact that there are already several fairly effective ways to stop the typical cuts-and-scrapes of a household, from regular band-aids and gauze to liquid bandages (which quickly seals off a wound and prevents bleeding, in about the same amount of time). The real application would be in situations where regular hemostasis measures cannot be used or are undesirable. Again, this goes back to microsurgery. In most surgery, hemostasis is achieved by either tying off the bleeding vessel with suture, cauterizing the end of the vessel with a Bovey (an electrical tool used for cutting and cauterizing) or a laser, or simply clamping the vessel with a hemostat. There are other methods, but those are the most common ones in routine surgery. Clamping the vessel is not practical in confined spaces (the hemostat takes up space), cautery can't be used in all situations, and you can't always tie off the bleeder. The self-assembling gel described would be a boon in those surgical situations, another "arrow in the quiver", so to speak. The aforementioned application in patients with hemophilia is also plausible, if less certain.
Sadly, the journal that they are publishing in, Nanomedicine, is fairly brand new and not stocked by my local library yet. There have only been three issues of it so far (June 2006, August 2006, and October 2006) and the latest is not on their website yet. I would really like to read that article in full.
Chitosan is a polysaccharide, not a protein.